More of a confession, a cautionary tale, but input welcome

This has been a helpful forum to find. I find myself wanting to share my story. My main question is if there's anyone else out there that shares my situation: short story - things started to go south in my marriage when one of our children started to experience chronic illness.

Long story: married 19 years. Our youngest child, now 8, has had chronic illness issues since the child was 2. Due to her issues, my wife became very concerned and the child was in our bed almost every night for many years. Sometimes to monitor health but also because it became a habit. I tried for years (not months - years) to ask respectfully that the child (sorry - using gender neutral to protect the innocent) sleep in their own bed when they were not feeling too poorly or monitoring was unnecessary. The most common responses was my wife was too tired to try to attempt to have the child sleep in their own bed (I offered to many times to lay with the child myself until they fell asleep), or the child became upset that they could not sleep with mommy. In both cases I would reach a point where the situation became emotionally elevated. Now the reason I wanted the child in their own bed was just to be physically close to my wife - to create an environment of intimacy even outside of sex - and yes, so that every once in a while sex might follow. But she experienced high amounts of worry and stress about our child, which is understandable. The problem is I was a roommate in my own room. I soldiered on, which in retrospect was not an emotionally healthy thing to do. I have codependent tendencies (my wife, while having her own issues, has no issues with alcohol or drugs, I just want to make that clear). So asking for this time to be physically close alone was very hard, knowing that she was dealing with constant worry about our child. About 2 years ago I suggested she get counseling to deal with her constant hypervigilance about our child's health (this child was never at risk of death, but experienced bouts of pain that lasted weeks, probably twice per year on average - with short bouts in between). In retrospect I probably should have suggested marriage counseling, but in my mind it was her worry that was the barrier. We toyed with the idea of me staying home a few mornings per month to have sex, but I wasn't just looking for a release. I wanted semi-regular non-sexual intimacy. We had sex during this whole period, but increasingly infrequently. I made every effort to support her emotionally - we sometimes talked about the child's health almost every minute we were together during a given day. I attended as many Dr. appointments as my work schedule allowed. I engaged as much as I was able, although I'm sure I seemed more distant as the problem started to seem intractable. The situation consumed her.

So I became despondent. About 5 1/2 years into this cycle I became so worn down that I started considering an affair. I realize at this point I should have sought counseling with my wife or at least given her "fair warning" and considered leaving if things did not change. But unfortunately I suffer from a personality where I have high emotional intelligence when it comes to other people but struggle in expressing my own feelings when I think they conflict with the needs of others or might cause them discomfort. This is no one else's issue but my own, but it contributed to my choices. I sought out an affair partner and found one. I'll leave most of the gushing for another time, but she is incredible - we connect intellectually, emotionally and physically in ways I have never experienced. She is literally the most amazing _person_ I have ever met, much less woman. She had been in her own 20 year marriage to an emotionally abusive husband. She had tried many times to seek counseling with him but he always regressed. I realize fully that she took more proactive efforts in her own marriage than I have and has exhausted all options. She finally initiated divorce a few months ago.

I've always told her she would never be my "mistress" (meaning if she was single I would not consider for one moment continuing the relationship as it was - no one should experience that type of imbalanced relationship, much less this woman who is amazing in every way). So now I am facing that exact situation very soon.

Having already made a choice which I consider to be a moral failure, I was not going to compound that by stringing this wonderful woman along. We have discussed a future together at length, but it is obviously up to me to execute. I can totally see us together an happy forever - quite honestly if I had sex once every two months with this woman I would still be the happiest man in the world. Just to answer some common questions:

1) how do you know she won't cheat on you like she did on her ex?: She has always told me how important marriage and fidelity was to her. She tried very hard to preserve her marriage and only entered into the affair when things became hopeless (for some time she could not have left financially, and was only able to recently)

2) How do you know you won't end up in the same spot in 2 years when the "fog" wears off?: We are two people that have been in committed marriages for nearly 20 years. Extraordinary circumstances (years-long neglect and persistent emotional abuse) caused our marriages to fray. We've been astounded by how easy it is to give to each other in ways other than sexually. I don't believe in soulmates, but if I had one it would be her. I would work every day to be the best husband I can to her. I did that for many, many years in my current marriage (yes, the affair notwithstanding)

3) What about your children?: For quite a while I have not been able to be father I want to them because of my unhappiness. I am still very involved - coaching sports, checking in with them regularly at night to make sure they are emotionally tended to, helping with homework and finding recreational time with them. But internally I've become very muted and I don't like who I've become, even if I still "Check all the boxes" in terms of what it means to be a father to them (yes, I know the affair injures them in ways they are not even aware of)

So, not wanting this to drag out I have not equivocated and told my wife I want a divorce. In the intervening weeks she has sought counseling for herself (which I advised years ago) and now admits that on top of all the stress of our child's illness she was repressed in many other ways due to circumstances of her childhood and wants to work to "change our patterns" and repair our marriage. She has even admitted that most of our problems stem from her behavior and says that I have been a wonderful husband and she does not blame be for where our marriage has gone (I don't believe that, in the vast majority of cases both spouses contribute to growing apart and I can see where I have contributed - it's not important in what proportions which spouse contributes)

Meanwhile, I have met the love of my life. I realize the best situation would have been to seek reconciliation or have a "clean break" before setting out on a new relationship. But I was naive in trying to get my needs met outside of my marriage while trying very hard to support my wife through her anxiety and stress surrounding our child. My wife is saying all the right things, an even trying to initiate sex (which she infrequently did even in the best of times). She has no idea about the affair.

I won't sit here and say that if I cut off all contact with my lover that I couldn't have a cordial marriage with my current wife, but there has been a lot of damage done. I believe that 5 years of neglect, despite a child's illness and in the face of me asking for reasonable adaptations, has cause me grave hurt. I won't be told that I shouldn't feel that. My lover (she's more than that to me but this forum is littered with men that say that so I won't pretend that it holds any more weight then their words) is really a once-in-a-lifetime partner. I respect her in so many ways that I cannot even enumerate and know in my heart she would be a faithful and dedicated partner.

I'm interested in whether anyone else has experienced this with a chronically ill child. Having read up on it, marriages with chronically ill children can experience 70%+ divorce rates)

I'm also interested in any and all opinions on this, no matter how supportive or critical. I'm at a point where, regardless of what "could" have been done, I have no interested in repairing my marriage. I likely felt that way when I sought the affair. But I fully accept that I am in the throes of an affair so that certainty could very well be influenced by that.

Thanks for reading