Mom tricked me into meeting her second boyfriend

TLDR: My mom decided it was a good idea to introduce me to her skeevy 2nd boyfriend thats also her chiropractor by inviting me to to lunch and planning ahead of time with him to take both of us. She is not only making illegal decisions but ones poor enough to make me genuinely indifferent to her happiness and I dont feel bad whatsoever. Fun fact: this has been going on for a year and neither of her other partners know.

Background: My mom and I (25F) have consistently had issues as I have gotten older, mostly that I have matured past 16 and she has not. My father and mother are still together and have "raised" me and my two little brothers together in the same house. They have had a very contentious relationship over the years, each talking trash about the other to us and leaving me to clean up all of their mess for the past decade, including one of my little brothers living with me for the past 4 years.

All of this to say that I have become very strong in my opinions of how absolutely, magnificently and horrendously fucked my parents decisions have been on several fronts and told my mom to pack sand on more than one occasion. One major one being when she tried to have me call her long distance boyfriend of 14 years (that shes never met in person) "Dad". BUT WAIT there's more. My mom is still married to my dad, with this long distance guy, AND when I went out to lunch with her a few days ago a random friend that I had never heard the name of asked us if he could take us out to lunch just for both of them to accost me with the information that they have been sleeping together. I was told later that this was all set up ahead of time because I never listen and she knew that if I drove myself to the restaurant that I wouldve just walked out. To top it all off? Hes her chiropractor. Hes met my brothers. He even talked trash about my dad to my face, wondering if he had any redeeming qualities and asking me if I have ever seen any.

I moved three hours away to be an uncomfortable enough distance for my family to drive to me and I hadnt seen her in 5 months. She pulls this with the ONLY time she had with me and instead of being offended, I am unphased by the sheer audacity, but still shocked for the lack of introspection.

If it wasn't for my brothers I would not hesitate to cut off all contact with my mother and I don't feel bad about it in the slightest.