My mom 46F is alarming obsessed with my relationship 27F I don’t know how to handle myself from going off on her, I need some advice?

My bf and I have been together nearly three years we truly love each other and I feel at peace with him despite the turbulence that occurs in both our lives. Both my sister and father have met him and it went great and they think highly of him so everything is going well in that aspect. However I keep my relationship very private from my mother because without fail she finds some fault in my relationship. To add some context I live with my family and recognize that moving out would be the only solution in which I could get away from her incessant negativity but that is not in the cards right now for me. In the beginning she was glad I met a nice guy and happy to see me with him but as time went on things shifted rapidly. She began to question the amount of time we saw each other per week, looked him up online, gossiped with my father about theories believing he was cheating, using, and disrespecting me. So naturally I was upset we argued and ultimately I suggested she meet him to that her response was that she had no desire or interest. I respected her wishes and continued on with life but after that things became increasingly draining for me. She made no hesitation to openly express her thoughts on our relationship, critiquing what he does and doesn’t do. It’s gotten to a point where I dread being around her because I’m starting to believe she hates me in general. I have to fight my own battles at home with her because she genuinely makes me believe I don’t deserve love and respect from her because A) I’m still in school pursing a degree and B) because I’m almost 30 and don’t have the typical life of a thirty year old woman. So with that in mind I hope that provides some additional information.

For example earlier today I came home from our weekly date we typically do Tues or Weds but due to schedule conflicts we decided Fri night instead. When I came home my younger sister proceeded to let me know that my mother began to interrogate her asking her things such as, "What time he picked me up?" , "Why it was on a Friday?", "If she saw me leaving with him?" etc.

This genuinely infuriates me because I don’t know why she gives a fuck. In my perspective it has been three years of this constant battle of trying to win her over because I only speak good about him even if things aren’t perfect in order to get her off my back but I can’t do it anymore. I have tried setting boundaries but she doesn’t respect them. I have tried to let her know that if I had concerns or questions I would come to her but in all actuality I can’t even do that because she’s incredibly toxic in general.

To add another layer of context she’s been with my father for almost 31 years and just a few years ago he was having an affair. They chose to stay together and make it work but she’s seriously struggling with letting the past go. I want to believe she just wants what is best for me and doesn’t want her children to suffer the way she has but in the same breath I can’t deal with her self limiting beliefs and projections.

Does anyone have any advice on how to navigate this or any words of wisdom I could use?

I am trying my hardest out here to foster and grow a relationship with my mother but I’m starting to question why i’m putting so much effort in the first place.