Body dysmorphia and sex - BDD

I’ve been struggling with bdd for a long time now, ive been to counselling for it and it helped a little. I’ve been with my fiancé for almost 3 years but for over a year I just haven’t had any interest in sex, I’ve tried but I don’t know why especially when I used to love it. I can try but I break down crying and feel horrible, I’ve spoken to him about it and he thinks it his fault sometimes but I’ve explained. I’m not really sure what to do and was wondering if anyone else has experienced this!