Tough situation, but I have been in your position before. Here's what was said to me that snapped me out of it: There doesn't have to be something wrong with the other person for the situation not to be right for you. You looked elsewhere for emotional fulfillment because you were missing something in the relationship you had. There's a solid chance that you asked for that stuff in various ways, but it was still absent.

You need to step back, take a very serious and clear look at your relationship, and make sure you're not glossing over the shortcomings just because you want to see the best in him. He could be a wonderful guy, and yet not the right guy for what you need and that's okay. Don't try to hang on or fight for something that was already incomplete just because you're afraid of starting over again. It WILL pass.

My first advice though would be for you to stop calling yourself stupid. The whole psych ward thing is way WAY too much. Give yourself a break.