Andrea - in your country, is it to your advantage in a divorce if you can prove H is having an affair? If so, I wouldn't just take his word for it that he's not having one - I would do some investigating and try to get some proof.
Not saying he is - but, many of the signs are there.
Also - while he is still in the house - I want you to start, right now, going out and having fun in the evenings. When he came back before, it was because he was afraid you might find another man, right? So instead of moping at home, let him think you are out dancing and partying and having a good time with attractive other men (don't actually date, but let him wonder what you are doing).
I think your H is just depressed and desperate for something to change in his life - but sometimes, kicking in his need to "win you back" before some other lucky man gets you is just what it takes to wake him up.
