Not enjoying sex

Hey girls I need some advice,
So a few days ago my boyfriend and I were gonna Have sex before I got picked up but he said that I "take too long". That comment made me really upset and I knew he regretted it as soon as he said it. I was upset about it mainly because I thought he was thinking that whenever we had sex but to hear him confirm and say it really hurt me.
Anyway, since then, sex hasn't been as enjoyable for me since I'm always self conscious about it now and he knows how I feels and apologises all the one. Today I actually broke down during sex and cried because of it. I know he feels so bad for saying it but I just don't know how to get it out of my head /: can anyone please help me or give me some advice /:
Thank you x