Gee, in_dire_need, I'm so sorry that you are in so much pain, and having to deal with this situation
I'm so very glad you've found us! Every member of this Board knows the sadness you are facing, and the behaviors your Husband exhibits do seem familiar to what we've all faced, too... .
How long have you been married? How long were you a couple before marriage? Did the marriage change the way he treats you, or were his hot-and-cold episodes similar before the wedding? Something I'd like to suggest to you is to read all of the links to the right-hand side of this page; you will find so much valuable information there that might help you understand what is going on with him.
My own Husband has BPD traits (I doubt he would be diagnosed with BPD, though), and most times he thinks I'm great--he's very loving, attentive, respectful, intimate, etc. But there are times, usually when I least expect it, where something I say or do will unintentionally offend him or hurt his feelings, and then he will treat me as if I am a stranger! Someone he doesn't even know, someone he has never even loved in the past; it amazes me that he seems to forget who I really am at those times. And amazes me that he seems to forget that he'd just thought I was a wonderful person and wife, sometimes just minutes before
The information at the links I mentioned explained to me just why/how that happens, and gave me the communication tools to be able to detach myself from his words and actions and react in ways that shorten those episodes and makes things better. I have to say, finding this site has improved our relationship immensely! It really helps to know that we aren't alone with this, and that others have been where we are and can help with their advice and insights
