I'm SO sorry for all you've been through over the last 3 1/2 years OP, it sounds like life has been really hard for you, and obviously the last thing you need is some idiot making things even more difficult just because he can.
As other posters have asked, could you, and would you, consider moving? I realise that if you spent a lot of years in your home with DH, it might be a wrench, but it may also give you a new lease of life, and would get you away from this man. On the other hand of course, there are no guarantees that you wouldn't be jumping from the frying pan into the fire, as you just never know with people, they might seem nice to start off, and then when they've sussed you out, they could become even worse than what you have now, so think carefully before charging in.
I don't know if you have received any counselling for your loss at all, but it may be worth considering, even after this length of time. Also, have you spoken to your doctor about how you're feeling, as it may be that you will feel more able to cope if you took anti-depressants for a while. Finally, is your DD supportive? You said that she visited, but does she see you/call you often?