Your H expects his W to make him happy. According to you, that is why he left the other two. Sadly, he didn't learn that he is responsible for his own happiness.....not his W.
You live in fear that he is going to abandon you like your first H. You are living and making decision mostly out of panic. You are allowing your emotions to be in charge of your life. Easy to do when your M is falling apart.
Your M problems are serious but very fixable. First thing, you have to become your best friend, okay? Look on line about women's self-esteem. You must have good mental health before your physical health improves. You may need to go to your doctor.
There is another on-line program that helps women learn how to organize house keeping and how you can do just a little every day and stay on top of things. It's been a big help to me.
Your H has taken a hard punch to his male ego. Loosing his job and almost all of his possessions had to hurt his pride a lot. Getting M was not the best thing to do right then, but can't changed that. I have been where you sit when my H was out of work for a long time and the bills piled up and he was not motivated to do anything around the house. It is easy for the W to start losing respect when she sees that side of her H. He's defensive and she's resentful.
The fact that your H is guarding his computer is not a good sign. I had a serious EA on line with OM. I could tell you all the reasons of why, but it's not important to your stitch. What is important is that your H stops that activity before things get more involved and there's a third person in the R.
So, have you set any goals for yourself The first of the year is a good time. You can have short weekly goals and long range goals, but have those that are attainable.
I think if you show respect for your H, and do it on purpose, it will help a lot. By doing it on purpose, I mean that you may feel that he doesn't deserve it....but you do it anyway.
It is hard for a man to be angry around a woman who is bright & cherry. Did you know that? Yes, it's difficult to show a happy attitude when the other person's stinks, but if you act from a determined heart instead of emotions....you can do it.
What can you do that would cause him to want to be with you instead of on the computer
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!