I have had a strained relationship with my DM since my early teens when she and my DF split due to her having an affair with not one but several other men. My DF suffered a breakdown as a result and I found out far too much detail as to what had gone on.
Without posting too much detail the amount of men she had slept with behind his back was very high, she had brought them back to our family home for sex in the middle of the day, it was all common knowledge amongst our community and friends and worst of all whenever my DF raised suspicions she would twist it to make him appear paranoid and unhinged. She even suggested that he attend counselling for his apparent trust issues - I think this type of behaviour is known as gas lighting? Eventually the only way that he could catch her was by hiding CCTV cameras and secretly recording her.
The resulting fall out and revelations ruined my relationship with DM and 15 years later things are still strained and tense. We do see each other once every few months but it's all very superficial and fake on both sides.
Since the breakdown of my parents relationship she has not had any official BF but I have found out through various sources that she is seeing several married men as their bit on the side including once when I came home early and interrupted her in the act. Whilst I don't condone this behaviour, I've buried my feelings relating to this generally and just tried to move past it.
The difficult part is that I have a much younger Dsis who was barely a toddler when my parents relationship broke down. She has been shielded from the reasons why and I have been supportive of this as I am saddened by my lack of mother-daughter relationship and don't want Dsis to suffer the same. Now my Dsis is in her late teens and has discovered for herself that our DM is seeing at least two married men currently.
She is very upset which is quite understandable and has confided in me. This has churned up all of the old feelings that I had and makes me question why I even attempt to keep a relationship going with DM when I can never truly forgive her for the way she treated my DF and her continued antics. She is a huge flirt and even flirts very obviously with my FIL in front of my MIL at family gatherings. It may sound crazy but I don't think that she would consider any man to be off limits including my DH (although I trust him I could never trust her).
I have a young DS and am expecting another baby in the spring. Being a parent makes it more difficult for me to comprehend how she could treat us as a family with so little respect and how damaging her actions with other married men could be to other families. I know that the married men in question are even more to blame and if they weren't cheating with her it would probably be with someone else but her behaviour and apparent lack of moral compass still sickens me.
One part of me wishes to go NC and explain to her why, the other part wants my children to be unaffected and have some kind of relationship with their GM. I hate the impact that her actions have had on me and how they've shaped me as a person (I've understandably had some trust issues in the past although my DH hasn't given me any reason to be) and I don't like the idea that her behaviour could affect the next generation.
If you were me WWYD? Anybody had any similar kinds of experiences?