Anxiety & insecurities

I’m not sure why but ever since my anxiety got bad i became really insecure & i hate it. It’s like I became manipulative & kinda psycho to my boyfriend, there’s this girl that is basically his neighbor & he told me his brother is having sex with her just for fun. Tell me why i overreact when he writes a comment on fb under his brother’s page & she likes it although that girl & my boyfriend don’t have each other on fb lol. Like i know i have issues i even be thinking that maybe it’s him having sex with her & not his brother. Idk if i need constant reassurance but idk how to stop thinking this way. Like we’ve had talks & we’ve agreed how he’s more mature than me & it’s true. & I’m not sure if i need to go to a psychologist for this & tell her “well i have issues with my relationship ever since my anxiety” like is that even a thing? It’s just weird that i know I’m worth it but at the same time i feel insecure because i feel like guys (in this case my boyfriend) can’t see it. I’m not sure if i made sense