Anxiety about the past

Hi everyone. I was looking for some advice on an odd issue. Me and my partner get on great, he always tells me how much he loves me and he treats me as such. However, I have horrible anxieties about his past and what it means for us. If someone comes up in conversation that he used to see or like, it makes me anxious and I worry if he still wants them. I feel like I worry about things no one else would think of. If we are watching TV or out for dinner I worry if he looks to long at someone (he never does) or if he finds someone more attractive than me and ultimately I worry I'm not good enough for him in the long run. I know these anxieties are probably fuelled by a previously very emotionally abusive relationship, but I wondered if anyone had tips about intrusive thoughts? I dont enjoy these thoughts and I never mention them, but it makes me feel horrible and I beat myself up over these things when I shouldn't and it isn't really my business anyways. Just looking for some help about how to manage my brain that doesn't want to co-operate with my general happiness. Thanks in advance