Well, that type of negative thinking can certainly cause one to feel anxious. I get into that type of thinking sometimes too. Very familiar. Anxiety could cause the thoughts or the thoughts could cause the anxiety.

Since you recognize the thought pattern, you can try to find a way to turn it around. My t taught me to put a rubber band ( thick one, not too tight but tight enough) like you would find on vegetables. And snap it every time you notice your negative thoughts. It help "snap" your awareness back on and then you can focus on what you are feeling, and try to get your thoughts back on track. I know it sounds really simple but it does work. There was a thread a while back uduing the same method to help with SI thoughts.

The resentment building up, and I don't really have advice for that besides trying try figure out how to come to peace with it. Better communication? "And I don't see how I can say anything now after 8 years, or what to say. I can't really say 'I'm p*ssed off because you did x, y, or z in the past' " Are you sure? Do you have a T you could talk to about this and be able to figure out a way you can communicate this to him, without him feeling attacked or leading to a fight. Sometimes it is really good to talk about this stuff. Just a simple conversation, like I am having trouble with this because of _______ . I'm not sure how the conversation should go but clearing the air a bit in a positive way can be a really good thing. It might allow you to be able to let go of it, and it could help him understand you better. Just an idea anyways.

There have been lots of threads similar to this on the bipolar forum. So I think it's something many of is do have in common. They always say that bipolar shares some symptoms with Borderline. I haven't looked into borderline much but maybe this is what they are talking about?? I don't know.

I know it's really not a fun place to be. I also go through the whole " should I break up with him" circle and he has not done anything wrong. I hope you can sort this out.