My (27 F) parents (52 M, 52 F) got divorced a couple years ago. It came out of nowhere, was a shock for me and my sibling, but it’s all good now. I’ve never seen my parents happier, and I’m so happy for them to start dating again; I want them to have fun and find love again.

My grandfather ( Dad’s dad) got sick in 2023, and it was tough. When visiting with my dad and grandmother, my grandmother mentioned flowers from a woman who I’d never heard of before. When I asked my dad who that was, he said it was just a friend who I’ll call Connie. I found it strange that Connie had been to the city I live in (my father lives 300+ miles away and was visiting his father) with my dad, and even seemed to be pretty close with my grandmother. My grandmother even had a nickname for her.

Over the next couple of weeks, I found out that my dad and Connie had been seeing each other since 2021, though he kept saying they weren’t dating. My grandfather, grandmother, mom, aunt, uncle, 1st cousin (all my immediate family) knew her pretty well too. My brother even spent Christmas with her and her family one year.

When I met her I basically had a huge breakdown. I apologized for being so upset, and she seemed to understand. My dad eventually admitted they were dating that night. I expressed how heartbroken I was that I was the only one who didn’t know. When I asked everyone else why they didn’t tell me about it, they truthfully assumed that I knew all about her. She honestly wouldn’t come up in conversations with them so that makes perfect sense.

After I met her my dad expressed he was upset that I talked to my mom about the situation, but in all honesty I feel my mom is the only one I could go to about this. He mentioned that he told me in the past that “My dating life is my business. Not your mother’s”, but he never told me he was dating, so how could that be true?

I have Borderline Personality Disorder, chronic depression, and anxiety; I’m the Black sheep of the family and honestly I feel he didn’t want to introduce me to her because I’m mentally ill (though he says that isn’t the case).

They aren’t dating anymore but I’m still incredibly hurt. He really does believe I’m overreacting and that it’s not a big deal. I feel I can never fully trust my dad again. We were extremely close (or at least I thought we were) and now I’m more distant with him because of the distrust I feel.

Am I the asshole in this situation?

(also if anyone has any advice on how to trust a person after they hurt you I’d greatly appreciate it)

Edit:

My parents divorced before my dad started dating her. the divorce was amicable and no infidelity was involved. please don’t view my father as a cheater, because he isn’t.

Another edit:

my breakdown was due to the fact that i fully realized i had been lied to, not because he’s dating someone