His ex said he abused her. He claims she abused him

I've been with my boyfriend for about 9 months now. He told me he was in a very toxic abusive relationship a few years back and what got him to finally leave was realizing she was turning him into someone he did not recognize. Also said she would stalk him. She had randomly tried to to message me on different occasions but this recent one she said don't believe anything he says and that he abused her. Her proof of that was showing me texts where he's calling her a fucking bitch. She didn't show any context to these texts. All the other messages are cropped out. All she's showing is this one text saying "You're a fucking bitch". This is where things get messy because I did speak to him about what she was saying. He had a DV charge but he wasn't convicted. However it was a situation where they were both arrested for DV. So when that happens it's usually when two people are fighting each other and the cops don't know who the actual aggressor is, so they arrest both. I asked my mom for advice because she is a domestic violence advocate so she ended up looking into their both their past charges. As I said he had a charge. Not a conviction. She had multiple conviction but a lot were from past relationships she was in and she was charged with stalking before. My mom said "I am not one to defend a man being accused of abuse over a woman. But honestly I think he just wasn't a perfect victim. There's no such thing as a perfect victim and that goes for men to. It's your decision what you wanna do but from what I was able to find I don't think he abused her. I think he just wasn't perfect." So with that information I guess I'm trying to decide what to do. That was my mom's advice which wasn't really advice.