MB - He gets anxious and upset around you because of guilt, pure and simple. OW has nothing to do with you. You're not even connected in his mind.
One thing I've read about MLCers is that they know what they're doing is wrong - they just cannot seem to help themselves. Whatever they are working through (past issues) has changed their brain chemistry to the point that the urge is unstoppable. It's really hard to understand - but I've done so much reading on the subject, seen identical signs in my own H - that I know what the experts are saying is true.
They've done countless interviews with people who have come out of the crisis, and they all say the same thing. They knew what they were doing was wrong, they just couldn't help themselves. They were fighting themselves the entire time, which is why they seem so confused at times. They are!
The important thing for you to realize is that there is nothing, absolutely nothing, you can do to change the course. ALL you can do is focus on you for now. If you keep watching him, it's going to keep hurting - because he's going to do things that are so contrary to his nature. He's not the same man. Everything that was "good" is now "bad". His morals? He's cut off from them. He's cut off, emotionally, from all of the things that mattered to him in varying degrees. His kids. His family. You had to become the villain to justify his bad choices. Somewhere inside him he knows that is not true.
Learn everything you can about MLC. Understanding it will allow you some compassion. That's the best you can hope for right now. MLC runs about 5 - 7 years. Can you imagine feeling the pain you do now for that long? Don't do it. Detach. Work on you. You've got plenty of healing to do from the hurt he's inflicted. Hurt that he wouldn't have inflicted if he were in his right mind, absolutely. It has to run it's course, MB.
If they return too early, it never works out. They are the victim of urges they don't understand and can't explain. Can you imagine having him come back for another 12 days, and then leaving again, over and over, for 5 -7 years? No, no, and no. You have to let him go. You have to let him resolve whatever is eating him from within, and he just cannot do that with you.
It is horrible. It is absolutely horrible. I'm right here, in the same place, with you. What if it's not MLC? There is that possibility - but many of the same things are true of an affair. Their brain chemistry is off, badly. It's like you're dealing with a heroin addict. They HAVE TO turn you into the bad guy, or the guilt of what they're doing would eat them alive. Personally, I'd rather they have guilt than an affair - but once it gets that far? It has to run its' course.
My H agreed to work on it, too. His heart was not in it. He absolutely cares about me. I can see it in the way he talks to me, his mannerisms around me...it almost makes it worse. I'm a little ahead of you. I've realized I have to leave him to his own mess. I haven't given up, by any means. I've just realized nothing I do will change the course he's on. He has to do it himself, or he'll just do it again. I couldn't deal with this again. Period. I'm just beginning to crawl out of the hole I've been in, and have no desire to go back.
I'm taking a chance, yes. But the way I've framed it to myself, is that I'm taking a chance for a future M with my H that is far superior to the one we have now. If I let him go, so that he can learn for himself that happiness is not to be found "out there", if he comes back, I'm going to have a properly remorseful H - one who is willing to do the work with me to have the M we both want so desperately.
H is not at the point yet where he really understands what he's done. He has to get there, or we're going to wind up at this place again. He needs to experience genuine, deep sorrow. He needs to fight to get his place back, so that he understands its' worth. I don't ever want him to leave me again. I couldn't survive this twice.
Am I happy with this? No. Am I content? No. But I do accept it. I do accept that our single hope for a better future completely relies on him crashing and burning. He needs to learn this lesson. I won't be willing to take him back unless he does. Now that I've accepted it, I've come to kind of a bittersweet peace. I'll work on me. I've got plenty to work on. I'll be happy in each moment, because I've got the privilege of still having moments to experience. That is no small thing. I know who I want to be - and I'll spend this time becoming the best version of myself that I can.
I hope my thought process helps you a bit. I know, completely know, just how much pain you're in. The process of getting out of that pain largely relies on how you choose to view your present circumstances. It's a hard concept to grasp, but once you finally do, you will find some peace.
You'll be able to give the best of yourself to your children, because they desperately need you to give them that right now. You'll reach a place of compassion and forgiveness that feels so much better than confusion and anger. You'll start to grow as a person, and that feels great! You'll have the comfort of knowing you're on the right track - you're doing exactly what you're supposed to be doing with your life: living it, learning from it, enjoying it, prizing each moment for being lucky enough to have the moments to live in the first place.
I wish, so very badly, there were a way to take some of this pain from you. I've shared what helped me: learn all that you can about MLC, make conscious choices about how you choose to look at different situations, and be thankful that there is a chance in the future.
It'll get easier the more you do the above. Time will pass. Acceptance will settle in. I can actually look at H now, knowing all that he's done, and feel compassion and forgiveness. That took some doing, let me tell you! I can be pleasant to him. I can talk with him about minor things. No R talks, no "I love yous", no deep conversations; however even that beats that hateful silence that was in place before I reached this stage.
It's hard, but it can be done. I promise. I suffer from Major Depressive Disorder, and came far too close to just giving up. I had letters written and a plan in place. I was freakishly calm about it, too. The pain was more than I could handle. It was the thought of my children losing not one, but both, of their parents to extreme selfishness that pulled me back from the edge. I love them enough to live for them.
Your H is confused, and it's showing. Once you learn more about MLC, you can almost watch him like a science experiment - and even that is a huge step in the right direction!