Always right

[Kayclan]

I find it so hard to have a conversation with my family member when she is always has to be right. It doesn't matter what the subject is. The more I try to explain things the more in a knot I get and suddenly I'm going down this vortex of seemingly no return. On the other hand I could just nod and agree but that isn't a conversation, that's a monologue/lecture. Aaargh will I ever learn?

[Methuen]

find it so hard to have a conversation with my family member when she is always has to be right.

Maybe it's time to change it up.  Could it be:
a) Time to have different conversations?
b) Time to have the same conversations but differently?
or
b) Time to have your conversation with a different person?

The more I try to explain things the more in a knot I get and suddenly I'm going down this vortex of seemingly no return.

Are you familiar with JADEing?

[Kayclan]

So I just read about Jadeing. I had learned about it a year ago and thanks, I had forgotten and now am reminded. I will practice this.
Another thing I find myself doing is giving an excuse for saying what I've said,  sort of saying sorry it was my fault. Sometimes I even apologise and she thanks me. But I end up feeling that I'm a villain. It doesn't always kill the conflict and I don't know if it is the correct thing to do.

[Methuen]

Another thing I find myself doing is giving an excuse for saying what I've said,  sort of saying sorry it was my fault. Sometimes I even apologise and she thanks me.

You can see what is wrong with this right?  How unhelpful this is for both of you?  These are like mind games, with the risk being that you start to believe some of the things you are apologizing for. 

But I end up feeling that I'm a villain.

You are NOT a villain.  BPD can be a terrible and complicated illness.  One of the best things you can do is read about and understand it.  Then learn some new skills (this website has tons of good info) for relating to a pwBPD to reduce conflict.  And start practicing boundaries to keep yourself safe.

It sounds like you may be "validating the invalid".  Don't apologise (directly or indirectly) if you have done nothing wrong.  Doing this validates the invalid, and just reinforces their dysfunctional behavior.

https://www.bpdfamily.com/content/communication-skills-dont-be-invalidating

Is it that you "sort of say sorry it was your fault" to keep the peace?  Is it a survival strategy?   pwBPD have distorted thinking, and you really don't want to validate that distorted thinking, or it is going to continue, or even get worse.  What you can do instead, is validate the emotion you perceive them to be experiencing, and empathize with them.  That is a healthy communication skill.  But apologizing all the time to avoid conflict could make you feel either like a doormat, or insecure about yourself. 

Does this family member live with you?

[Kayclan]

Yes this family member lives with me, at the moment as she is looking for her own accomodation, but it's been almost 2 years.When I apologise it's because I feel trapped into a corner. Yes I do apologise, more to keep the peace, because by that stage I have found no other way out of the hole.