Why do you want a relationship with a woman who lies to you early on and one who would be immature enough to "get off" with your 27 year old colleague? Any woman who would do that to get back at you bc you were busy at your own party doesn't really care about you- she is selfish and cares more about herself and her own needs. This is the type of woman who would do the same thing to you if you ended up with her. Honestly it seems like she is leading you on and enjoys toying with you. You are 46 (old enough to know better and not be interested in these immature games she seems to be playing).
What you have isn't love- it's more like infatuation for something you wish you had (bc you haven't even had a relationship with her and you honestly don't know her that well).... she is young, flirty, and something out of your reach right now. Yes, anytime you talk to someone (text, email, etc) all of the time for awhile you get used to it and yes it is always painful when you have to stop contact with that person. You miss what you were used to doing but the simple fact is what you were doing is wrong.
Marriage is a sacred vow and her husband has asked you to back off so they can try to work on their marriage. You should really respect him (and your wife) enough to do that. It may be painful but you need to block all contact with her. Again, you should do this for YOUR sake but also out of respect for her husband and your wife. If you truly want to find someone else, you should at least divorce your wife before you start anything with another woman. You didn't mention your wife and your relationship. Do you love her or care about her at all? Does she know? Are you really willing to sacrifice your marriage and your kids for a woman who is just playing with your emotions?
Then what about trying to rekindle the romance with your wife? Instead of sending flirty, sexy text to a married woman, why don't you send them to your wife? Send her a little gift, leave notes, etc. Do the things for her you are doing for this other woman. Maybe even get a sitter and plan a night out of town to wine and dine her (and put a little spark back in the relationship you have). I think you need to put the energy you put in this "relationship" into trying to rekindle something with your wife.