So sorry to see you here, but this is an awesome place to be and you will find alot of support here. Come here often as the people here understand what you are going through, unlike friends and family who only want you to be happy so their answer is for you to leave him and punish him.
I think the fact that your husband wants to see a C is a positive sign. Now I'm no expert here but I will offer my advice.
My sitch--M 14 yrs, tgthr 20, 3 kids-d-13,s-10,s-9, bomb dropped on June 1, been separated since Aug. 11. Things are going ok but long way to go (you can read my threads by doing a search on my name)
The first few months I was just where you are, in a total panic (although with mine this was totally out of the blue, our M was perfect or so I thought) I did everything wrong, I begged, pleaded and tried to show him how much we were hurting. All this did was drive him away more. Now I am accepting what is happening and I know that it can go either way and I have to be Ok with that.
The fact that your H has told you that he doesn't want to let OW go in case you don't change is showing you that he is being honest about his feelings. I think this is a good thing. H is not hiding anything from you. As odd as it sounds, with him being honest with you now I think it will be easier for you to learn to trust him again. Things he will say to you (about when he is going to be with other woman, not about not ever being happy with you) will hurt but at least he is being honest, telling you how he is feeling. If he holds things in that is not good for either one of you.
For you to demand that he stop seeing OW will be viewed upon as control, and that is what he is rebelling against. So as much as it hurts you have to let it go. (again I am not an expert, I am only talking from my situation) If he is in fact having a MLC then this is his journey and you have to let him take it or it will happen again. You have to stand back and ride it out, if that is what you want to do. The choice is yours to stay or not. If you do push him he will run and might not come back. If you just ride it out he may come back and if he does it will be because he wants to and he wants you. We have no control over others just over ourselves. Come here often for support. Check out Hearts Blessings posts, reading them has helped me alot!, she is very wise.(just do a search on her username and her posts should come up)
If at all possible do not react to things he does or says without thinking about it for a while. It helps to step back and think, if you react first you can't take back your actions later and you will only confirm what he is saying about you.
You will have to be very very patient. this will take time. But the more you push (if it is MLC) the longer it will take.
Tina
M 14 years, tog 20. 3 kids D-13, S-11, S-9. Bomb dropped June 1/02, sep Aug 11, living with OW since Oct/02.