Dom, yes, I know...believe me, the moment I said that, I knew what the problem was. He actually thinks we're not playing relationship....he told me he just thought we were 'really cool for the baby'. Um, yes. Except for the parts where we budget together, lend each other money, talk tens times a day about intimate feelings, have keys to each others' place, plan our days together, and yes, have sex. Sounds like a boyfriend to me! (Okay, that was venting...although I presented it much better here than I did to him...)
It's not like I was expecting an "Oh my God, we should just be married!" from him. Just that he understood what he was doing. I wasn't even asking him to stop hanging out with his friends or to cut off JD. I just want him to see what this is.
To be fair, I did a really bad job of presenting it to him. Timing was wrong, and I was way, way, way too emotional. He did seem very open to my explaining it--I just blew it and called him a cake-eating narcissistic @$$. (Yes, I know.)
So...backstory...I did the snooping thing. It wasn't completely random timing on my part; it was triggered by something very odd he said while we were fooling around. I knew he sent stupid ILY's to JD. Not news. I saw more of those. Then I also saw messages talking about "what's between them." xh still won't call her his gf, which p!sses me off for two reasons...
For one, I think as long as he doesn't 'label' what he's doing with either of us, he thinks that makes it okay. Two, if he won't call her his gf--while sending her cutesy messages--that shows a whole other level of disrespect for the women he is emotionally involved in.
Oh...and I guess there's three...... So, if he's been speaking with her like this for as many months as I think he has...there's no way they haven't become physical. (I'm not that dumb. He won't tell me either way.) It's not that they'd be sleeping together that's really upsetting to me...it's that he'd be sleeping with her, telling her he loves her, and then come back, play married with me, and sleep with me. And that it appears he doesn't see anything wrong with this.
So. I don't believe he's intentionally playing us both--but that is what he is doing. I do think he is open to having a rational discussion about it; I simply did a miserable job of talking to him about it. What few points I was able to calmly make, he said "I could see how you thought of it that way." It's not any one thing; it's the accumulation of them. And I was just totally blank at the time because I was so worked up. (This is a problem that I have in general.)
My plan is to take my time, write it out all in a letter, post here for feedback, and let him read through it. I will most likely have to pull waaaay back emotionally after that. I am trying to prepare myself for that; I think he needs to learn that this is not acceptable.
I also suspect he's more attached to me than he realizes. (He was very worried about me earlier during my extended prayers to the porcelain god. Ugh. Ate something bad or something.) I don't think it will be very pretty when I try to establish stricter boundaries. He accused me the other night of trying to use the baby against him when I said I felt the overnights were part of the problem. His response: xh refuses to spend one night away from the baby; therefore, he is justified in having a key to my place and sleeping over here. (Although he did offer to sleep on the couch.) Yes, I know how completely messed up this is.
Do I think he's capable of learning from this? Actually, yes I do. xh has learned that his behavior 2-3 years ago was inappropriate for a married man--and that my getting upset about it really did not make me a controlling person. (As I'm sure he is thinking I am now. His problem, though; not mine.) In addition, we both used to just not be bothered by a lot of this kind of stuff in the past. Neither of us saw the harm. Well...I've been learning...and so has he...
I think the key is, that I need to present it rationally (unlike last night), and the actually follow through with drawing back. I am worried it won't be pretty; but this is about how I will and will not relate to him.
Sorry if this is all a jumble. I'm still not feeling very well...mostly just stream-of-thought writing to clear my head.
... So, if he's been speaking with her like this for as many months as I think he has...there's no way they haven't become physical. (I'm not that dumb. He won't tell me either way.) It's not that they'd be sleeping together that's really upsetting to me...it's that he'd be sleeping with her, telling her he loves her, and then come back, play married with me, and sleep with me. And that it appears he doesn't see anything wrong with this. 
