my boyfriend is thinking of leaving me

So last Saturday my boyfriend found out I went on a date with a guy when we split up a while ago he is now saying he needs time and might not what to be with me anymore. he said to leave him alone so I have, he keeps sending me nasty messages saying that guy is welcome to me he hates me ect but what I don't get is he also went on a date when we split and I wasn't really that bothered by it! But he said that's different! Double standards here or what?! Now What should I do? He says I have hurt him and he is a mess and he can't forgive me... Any advise ladies