Thank you Jones, it helps to talk it through.
I don't think he is using his BPD to hide behind, although it does seem like that sometimes, it's bad enough that I had the EA to deal with, but the man I married disappeared and left me with this mentally ill one where I have to worry more about how he's feeling than how I'm feeling.
I honestly don't know if I love him or not, when he asks me I say 'no,' every time he says 'I love you' to me it just washes over me, what use is love if it can't protect against shit like this? I suppose I want it to be like in the movies, where love conquers all, in Indiana Jones & the Temple of Doom when he's hypnotised to kill Willy, but in the end he comes back from it because he loves her. Childish I know.
I feel like Ewan McGregor in Moulin Rouge where he says to Nicole Kidman 'thank you for curing me of my ridiculous obsession with love.'
But I think I must love him, I know I care about him. I certainly wasn't hanging around trying to repair our marriage because it was the easy option.
The thing that hurts the most is how cold he can be to me now. Before he got treatment for his BPD he would never say anything in anger to me, even when I deserved it (God knows I've never been perfect). Now he says it's like the box that he was keeping all his emotions in has been opened and now that they're out they won't fit back in, so I get him being shitty to me at a time when I really don't deserve it and really can't deal with it. 
This morning he said he had something to say, something that he said he didn't want to say but he had to, and I thought 'this is it, he's going to confess that he did sleep with someone at work.' And this calm washed over me, a cold calm and I found myself thinking 'right, how am I going to deal with this?' in such a relaxed manner and it was a relief, for a split second, I was finally going to know the truth.
But then it was just to say that he's not going to get better while we're still together, which, to be fair, I have been saying for ages. And I was disappointed, in that moment before he spoke, my mind had been peaceful, something which it hasn't been for over 10 months. I just wish I could know the truth, whatever it is, because if it turned out he had slept with someone I could at least deal with it, instead of my brain forever running around looking for answers.
Wow, that turned out to be quite an essay. 