Lunatrope,
I'm thinking good thoughts for you and I'm hoping that things will work out. I can feel your pain as my wife recently left me and it turns out I had been depressed for a very long time without understanding what was happening to me. But, in the end, the undiagnosed depression was the source of many of our problems. Now that I know why I was pushing her away it's hard to sort it all out.

There may be some ways for you to save your marriage, but I'm not so sure you can do it solo. You both have to make it work. I think you should tell your husband how you feel about what's happening and what you are willing to do to keep the two of you together. Good communication is something my wife and I struggled with and after all that's happened, I really believe better communication would have made all the difference.

If you're as honest and open as you can be about how you feel, and you're ready and willing to do the things you say you will do to save your relationship, I think that's the best you can do. And if it still doesn't work out, you'll know that you gave it your all and you can be proud of that. The BPD will likely try to tell you otherwise, but in moments of clarity, you'll see that you did something very great and important- you gave it everything you had to give. And that's worth a lot! And so are you!!!