Hi, I also have problems with my son and can relate to what you are writing and feeling. I am sorry for what you are going through.
I also have given all I have to being a mom (especially because their BPD dad has been very little available for the kids) and yet am in a situation where my son is lying to me and about me at school and to officials and seems to have no limits or remorse in doing so just to get his way, no matter the cost.
Honesty is one of the most important values to me and that’s what I’ve tried to teach him as well, not succeeding obviously. Grief of loosing the relationship I used to have with him and the one I had hoped it to become and also strong feeling of failure as a mom.
While I also try to figure how and where to go from here, I don’t have good advise to offer, I just wish to let you know you are not alone. Please be kind to yourself and take care of yourself