Saw my ex’s now gf and I’m spiralling , I don’t know what to do to stop it

So I did have a hunch that he is dating someone and I know it’s none of my business knowing what he does or who he does and I am over him but I ended up using my detective skills and ended up finding his now gf on Pinterest lmao fml and she’s so so pretty like so pretty , skinny more specifically if I may add and It’s just hitting me so hard , I’m already very insecure about my weight and she’s like -15 kgs compared to me and I’m just spiralling so bad thinking about his friends comparing me with her, I dont want to be with him but I can’t help but compare myself , this was my worst fear and it happened.I looked at my photo after I looked at hers and it’s just so so sad how much I hate my body.
I hate that I can’t help but compare myself and now because I want to look better than her , i wanna loose more weight and i am scared that i might get a really bad ED but its sad that i feel like if it helps me get skinnier i dont mind. She’s so pretty tbh even I would date her. And it’s even worse because I’m bi and it’s actually really shaken me up alil since I like dressing up more androgynous and just seeing her all girly and feminine is making me feel those feelings again of being less of a woman and it has taken me years to accept myself that Im not less of a woman just because Im a little over weight or because I don’t usually dress feminine , also because I know my ex likes girls like that and I could never be that. It’s kinda shaking up my principles at this point . Idk what to do about it , it would really help me if someone could give me some advice.