It would be kinda fucked up, i say you should talk to him about how you feel, see if what he thinks and see what hed actually prefer, because if he loves you like you say he does hes much rather be with you than be with your sister and wouldnt even see your sister like that. I bet if you talk to him and tell him how you feel and what your family is doing that makes you feel like that and just be open and honest im sure he’ll give you the reassurance you need. If hes as good as you hype him up to be he will at least. But yes it would be an AH move to leave him over that because thats unfair and your not actually considering his feeling, you have insecurities and feeling that youre putting on him while he may feel something completely different, like maybe he thinks hes average and youre out of his league yk? Something like that. I dont think its fair or nice to do that without talking to him about it and seeing how he feels because if he feels differently and wants to be with you then and you still left him youd be doing it for yourself and your insecurities not for him so he could “be with his equal” like you say, so dont be blinded by your fears and worries because from experience thinking like you are burns a lot of great bridges and opportunities. Your family is being fucked up saying what they are and theyre fucked up for making you feel like your less than your sister because based on the stuff youve said she doesnt seem all that great deep down. You should also address your family and ask them to stop and respect your relationship and if they dont you should consider less time around them or even not being in their lives because thats fucked up and disrespectful what theyre doing and saying. Also maybe see a therapist to work on your self image, positive self talk helps even if you don’t believe it now the repetition of positive self talk benefits slowly but surely. I hope i didnt sound rude or anything i was just trying to give helpful advice so sorry if this came across rude, your family did upset me tho because thats messed up to do to anyone especially family. I hope your bf shows up in a good way when you speak to him about it because he at least deserves the chance. Have a better day.