Hi,
Honestly dont know. They sadly create fictions in their mind as to who did what and then run with them despite they are not based on facts. I never even raised my voice to my ex yet I somehow was the boogey man.
Bottom line as annoying as it is, you have to accept they are sick and it is essential they play the victim. To do this you have to be the bad person even if you were the saint ! Another way to look at this sometime you pass sadly mental people on the street muttering to themselves. Would you or do you pay attention to what they are saying ? Your BPD ex, is if anything, despite appearing outwardly normal just as sick as the person in the street.
As much as I would like it you cant control them. ? After being harrased and threatened ... .having my property damaged post breakup with my ex I sent her a stern NC email. This was after a visit at 1 am to my house and her threatneing me . Nothing too bad in the email just No contact of I will have to go to the police ... .no calls ... .emails or turning up on my property. Well this was after at least 10 similar incidents post RS ... .threats on her part ... .damage to my property smashed windows ect ect.
Anyhow she waved the email around not mentioning to anyone what she had done out of context and claiming she should go to the police as I was threatening her ? Anyhow next time she came around I taped it, went to the police so it was on record just in case.
An aside but its how their minds work. She went nuts because I said I wanted nothing to do with her and if she breached it I would go to the police ... .this is a person that smashed windows threatned me ... .my friends ... family and so on.
So will it ever stop ? Likely not. sadly they re-write history in their minds and it was funny to have a tape of someone in a rage threatning to kill you and your friends and me just calmly going please leave me alone I want no contact none ... .
Again this doesn't relate directly to your situation but I suspect most if not all BPD people operate this way with the rewriting of history. They really believe it !
Will they stop ? Likely no. They sadly actually believe their own new version of events. I am totally sure even if I presented my ex with a tape of her threatening me it would not change her version of events one iota.
Can you fight back against villification ? No sadly you appear like the boogey man. Only way is to disagree with the version as presented and not go too much into details as you will look as nutty as they are if you angrily try and defend yourself.
None of this makes it easier. With my own situation I just point out her first and second husbands and suggest they speak to them as to why they also will not have anything to do with her. Nothing

For yourself and myself ... .I live my life as best I can. Out now 13 months found a new beautiful person and am very happy.
One other thing these people telling you stories. STOP THEM ... .he is your past. Some in a small town are just mean and do it for a reaction ... .others mutual people we know some without fail will mention my ex ... .its not just unthinking on their part ... .some sadly are just not human and I avoid these types now.
None of it makes hearing something that is untrue easier but fighting back is not an option. Whilst a male ... I was at the wrong end of the abuse side not just verbal or cheating but spat on hit kicked ... .things broken and being told I was in some way the monster when the exact opposite was the case I found impossible to deal with until I took action and taped her in full rage. For a man accused of something horrible by a female there is not much one can do other than what I did.
In the end I dont care anymore. People will believe what they care to and my friends are my freinds ... .those whom I thought were my friend pre breakup are a different set to what is the case now. Strange but some people who were the kindest with my recovery were some who were not my friends but my ex's and had seen the game before. Even her mother took the time to tell me the real history and she had hoped I was the one who could make her happy.
For you, hold your head high and be proud !
You did the right thing and if someone starts ... .STOP THEM ... .if like me some cant help themselves aviod them. If you cant tell them in no uncertain terms what you think of people like them who cant help themselves.
I wish you well ... .easier said than done. A good person all their lives made out as some sort of freak or monster ... .only revenge is to live your life and live it to the fullest. I have ... .happy as Larry 13 months on ... .give yourself a treat ... . important to not get your kids choosing sides !
Live your life to the fullest and hold your loved ones close ... .your son will not only benifit from not being bitter about the ex ... .he will see you being happy and it will drive your ex nuts. More importantly you ... .you will be happy and fufil some dreams.
Take care on your journey ... .sorry for the ramble but been there other side of the coin.