My boyfriend cheated on me with an ai

I was messing around with his phone and I found out he's been flirting with an ai. I'm not sure what to make of this. My friends have been telling me to dump him, but I'm not sure about it. I can't help but feel like it's my fault. I've always been insecure, but this just put it over the top. I don't even know how to process this. I'm not sure if I should be mad at myself or him. At least if he had a real affair I could just blame him. I don't know why this is killing me so much.