What to say to the other woman that doesn't know of you?

My BF and I have been together 4 1/2 years. We got pregnant really quick and everything was good for pregnancy and until baby was born (except the sex went away). We now have a 3 1/2 year old. Our relationship has had it's ups and downs but he still comes home to me/us (my daughter and I) we do things together and spends money on us as we are a family.

My biggest problem is he is very closed he doesn't like to talk. We've had a few conversations about things and it always goes bad. When I ask his friends why things are different he tells them I'm not the same girl I used to like to party and drink and now I don't. I used to be this fun blonde. Yea since I heard that I went back blonde lol. But my priorites changed we have a kid. Did his? No he still goes out on his nights off and stays out till last call recently more so had a few nights he didn't come home till 5 or 6 or 7 in the morning. But he always has an place he was.

I found out about 10 months ago he was on POF and still using it. I had a friend tell me. I told him he told me he would delete it but now he has the app on his phone. Oh, and his phone is a whole other issue he's very private about it but when we first got together I didn't have a smart phone and he let me use it for facebook etc. Not anymore if I am caught touching it he goes crazy.

We had a conversation about me snooping in the beginning but I try to catch him leaving it around and maybe 1 or 2 times a month I can get my hands on it. I really don't want to as I see what's going on.

I went through a 4-5 month period of him sleeping on the couch and could hear him talking on the phone he'd come in late sneak the door shut of sleep on couch. Well one day I got smart and listened through door and even opened door and listened heard things I didn't like I addressed them with him. He to me lied but he could be telling the truth. But I also don't believe what happens in vegas stays in vegas either... not that he said that but it's along the same lines.

More recently I have found various names with POF at the end letting me know he met them there. I find them sending him nudes. Talking about things in the most inappropriate matter. But more recently this 1 girl with a local area code concerned me that I used my previous background as a background investigator to use. I took the number found out everything found everything on FB and even got her local information. It pisses me off cause she is here in the area and this one is easy to get to or call for a date.

I got his phone and looked through the pictures and found some of what looked like his land on a female body. NOT MINE. And I lost it inside. I read all the time that they talk and he wants to kiss her lips and how beautiful she is. These are all things he doesn't tell me anymore.

Now before you judge me I am the kind of woman that will tell her man just be honest with me and we'll be good. I am also the kind of woman that will work on something till it burns me (yes that's the bad part). I will forgive way to much and I don't just let things go without a fight.

He is the type of man that is very clsoed doesn't like to discuss things or talk about them so I tippy toe around the facts and let stuff eat me alive. If I talk about the wrong thing at the wrong time or send him a long text message he looses it like "I'll get another long text message from you" and he never responds.

So talking to him isn't the issue. I found this a while ago and had an app on my tablet and messaged anonymously these people. And he did bring it up one day saying one of his friends said they got a text saying something like. "They said they got a weird text saying someone they know might not be truthful with them they may have a whole other life" .... i said something like that not directly.

So with this one since I feel they meet up for dinner, I know she's a single mom, she knows he has a daughter but no idea what she knows about me. Probably nothing I'd like to anonymously contact her and say something to the like. I've thought about having a friend do it but why. I know of a app I can use to anomalously text her but I have no idea what to say. Sucks that deep down she's getting hurt just as much as me cause she probably has no idea. In my eyes a smart woman would always look into someone new in there life like that but... women don't think smart when it comes to men sometimes. I know I don't.

I don't need to know I need to leave him. I want to address the problem I know how his brain works. As I said I believe in forgiveness and working things out. I think there can be hope for someone regardless it's always worth a try.

So what should I say to this "other woman" that has no idea of me, and I'm pretty sure of that. I believe they met on Plenty of Fish. Her FB profile is very private. I dont' think I could do that anyway. And the only way it would work is if it was anonymous. I've thought about asking a friend but I think that might make it even weirder cause I can't control the conversation. So what should I say or do. Keep it simple or just say you've been talking to xyz he's got a girl and a kid and a whole life with them. SO CONFUSED AND CONFLICTED