Don't beat yourself up about past "mistakes". I'm sure that you are doing your best in a very tough situation and so long as you learn as you go then there really aren't any mistakes. You're one tough cookie for sticking with it like you have.
I'll bet a lot of people here understand the problems you're having with the "act as if". After a while, you get worn down and don't want to "act" anything anymore...you want things to be good without having to try so damn hard, right?
What do you think about the idea of taking a little break? Maybe a trip to see some family? It might help to get away from the situation and recharge for a while? If you can't get away, one thing that has helped me re-center is to make it a regular habit to take a walk. I'm not sure where you are, but it is Spring here those short walks, where you can enjoy the sun and the wind and the smells, can really take the edge off. And the exercise helps too.
It's kinda a funnny chicken-or-the-egg situation, yes? Making things "normal" requires that you are able to relax and be happy but relaxing and being happy *seems* like it requires a normal marriage! The real challenge is being relaxed and happy even though the marriage is in a tough spot right now but if you can do that...
