welcome @Cheesecake20- it's nice to have you here!!
relationships can be tricky to navigate, but it's really great to see you reach out here. i personally don't have bpd but i have struggled with my body image and had similar thoughts to you about someone hating me or leaving me. having trust in someone can be difficult, especially if you've been hurt before. talking to him about your fears can maybe help you feel more reassured in the relationship, let him know why you're worried and maybe think about what would help you feel safer/secure in the relationship.
the way i see it, he CHOSE to be with you as you are. i know it's hard not to think about our appearance or fear someone abandoning us, but remember that you are WORTHY of love. you are worthy of being with him. when people choose to cheat/hurt their partner, it's not the partner's fault - its because of themselves. it's a reflection of their poor character.
i hope others with bpd will be able to pop in to share some more tips and support soon too. wish you all the best with your relationship 💙