AITA? Mom issues pt.1

I forced my mom to breakup with my stepdad because he cheated. I waited 3 years but gave an ultimatum in the end. She believed he deserved a second chance and that he's done more right than wrong. I thought the weight of this one action outweighed the rest. In my point of view, I've always viewed him as a serial liar. But I never called him out for it. He lies about small things, often. I brushed it off and pretended to not know...idk, to not embarrass him I guess and maybe somewhere between a fear of confrontation and respecting his boundaries. For example, in the last trip we had together he'd lied about the amount of money he brought (he brought more than needed). I only caught him because he accidentally slipped in a conversation. The thing is, they just had a heated argument about moneh in the trip, with my mom saying he's spending too much on his daughters (he wanted to shop suitcases for them or something), and shouldn't do it now because they might run out of money. Idk, I just- why lie? And why hide it? The whole cheating was revealed in the most chaotic crazy dramatic way possible too. The girl he was with was ALLEGEDLY (not sure where info is but one of my family members dug deep in social platforms and had a conversation with the girl who reached out to them first and that's how it surfaced) in her 20s (he was in his 40s, while his DAUGHTERS were also in their 20s. Me and my sister are in our teens. This part still traumatizes me. Especially since it felt like he had touched me a little too low once). Also that he made an entire fake identity, changed religions, and married her or something? I hated (I like to think it's gone now though) that he portrayed himself as a such a family man. The type to say he'd protect us. Also alwyas paranoid that my mom would cheat; misogynistic at times because he'd said once that "girls shouldn't wear revealing clothes because they're just asking for it." Like he gave me the ick countless times. Con in nxt post