I haven't posted to you in a while but I have been keeping up with your sitch.
I understand having to co-parent with your H because I'm doing the same with my STBX. We are doing joint custody. I'm friendly with him but I'm not his friend. If you had a "friend" that treated you the way your H is treating you, would you remain friends with that person? I've asked myself that question and my answer was no. I can't be his friend because he feels he can tell me everything that is going on between he and OW#4. When he starts talking bad about her I tell him I'm sorry but I don't want to hear it and he usually stops. It's not that I'm hurt that he's with OW#4 because I've finally gotten over my STBX, it's just that he will continue to be the same man he was with me, OW#1, #2, #3, #4....He thinks everyone is the blame for his problems.
As hard as it is please do not have sex with your H. He will only be using you for just that. I made that mistake last summer hoping that it would make a reconnection for us, but it didn't.
Your H still wants to be involved with the OW. I've seen it time and time again with your H as I did in my STBX with me. OW is not completely out of the picture with your H. He even said he was going to try 100% to not to bother OW and her BF but he knows that won't be possible. It's just another line he's telling you.
Kissak, as I've said before you need to distance yourself completely from H and his drama. From what I've observed you began to get worried about H completely leaving/divorcing you when you believe things are rosy between he and OW, however, once H tells you there are problems between OW and H you get the sense of relief and you start seeing H as being the person you no longer want to be around. I understand this because I too did the same. It only gave me false hopes.
I've also noticed that you put too much thought in what H is doing, thinking, feeling and you really don't know what is going on in his head and he probably does not know too. You need to push OW thoughts out of your head.
I really don't mean to sound harsh with you I'm just going by my own experience about what worked for me and what didn't. Your H sounds like he could be my STBX twin.
M:43 H:37 D14 (ours) D18 (mine) S22 (mine) S18 (his) S: 10/2004 Bomb: 2/15/05 In/out of home Living with OW #4 Talks of D for 2-1/2 years