Hi Hulu,
Anyway he stayed and we actually had a lovely Christmas. He even said it was one of our best christmases yet! Which it was. Now, the issue with him in the past has been he tells his mum lies about me. Like, I assaulted him ( I didn't) I was prepared to defend myself when he turned on me. That I am crazy and launch personal attacks on him at any opportunity ( also not true).
I see two possible reasons why your BPDh told your mother-in-law what he did.
(1) In my observation, people with BPD (pwBPD) have their disordered emotions (of fear of abandonment/betrayal/denigration) triggered by feelings of intimacy and closeness. So in a sense, the "lovely Christmas" you experienced with him triggered him to also experience these disordered feelings that he is being attacked. And of course he couldn't express these feelings to you, because you would probably be unable to validate his feelings, because his emotional experience does not coincide with your emotional experience. So he spoke to someone who could reliably validate his feelings, his mother.
(2) A way to cope with these disordered feelings without actually dealing with them is to engage in the "drama triangle" in which someone is the victim (him), someone is the accuser (you -- even if only in his imagination) and someone is the rescuer (his mother). This behavior is also known as triangulation.
I feel confused about this. My husband had responded that he was looking forward to our holiday ( going to the coast for a week next week) and that he hoped his holiday remained tirade free.
I do not know what to do. Is it normal for pwBPD to tell lies to others like this? I am feeling very confused.
It might be helpful not to see his behavior as lying but rather as a complicated compartmentalization of his life. He probably wants to have a good intimate experience with you (which he does) but he also needs his coping mechanisms to deal with the disordered feelings he also experiences. Eventually he may accuse you of doing these things he perceives. But for now, he is maintaining the peace by expressing these disordered feelings to a third party who validates his feelings (even though they are disordered).
He is not doing this to be deceitful. He is doing this because this is he best way he can manage (perhaps without necessarily accepting) his disorder.  :)enial is a coping mechanism.
Of course I was very upset and spoke to him about it when he got back... .he just said I shouldn't be reading his private messages ( which is true but I pointed out it was there in all it's glory on a huge laptop screen, which he understood). However, since then I have found it difficult to trust him. I haven't snooped since then until after Christmas.
I understand that it is difficult to trust someone who (probably regularly) mounts a distortion campaign against your reputation but I see this as a typical behavior for pwBPD. It comes as part of the package.
I guess the real question is if I do not trust him that much to act like then then I should have a serious think about calling it a day and having that conversation with him.
And this is your right and a valid consideration.
The thing that irritated me the most was that things had actually been pretty good so I guess I am questioning why he is giving someone else regardless of who it is a totally different account of our reality. Why make it out to be bad when actually it isn't... .like I said no arguments in 6-7 months... .we couldn't go 2 days without major meltdowns that caused huge issues. Suicide, domestic abuse, police etc etc. So, this is a huge difference.
Just because it is not your reality does not mean it is not his reality. His reality comes with the distortion associated with borderline personality disorder. And some pwBPD learn to develop constructive behaviors to help deal with these distortions. Others do not and so live lives with much conflict.
I hope some of what I write is helpful to you.
Best wishes,
Schwing