For what it's worth, I don't think it's selfish of you at all. We all need a bit of space to regroup or reconnect with ourselves, whether we're having a bad week or a banner week. If he's trying to make you feel selfish, then just accept he has self-esteem issues.

I am concerned by your comment that he 'hurt' you...was that physically? If he's being abusive in that way particularly, I believe you should distance yourself from him on a more permanent basis; hurting you emotionally isn't much better. In either case, along with sorting yourself out, I suggest you sort out your relationship with your 'partner' as well. Abusing drugs because he hurt you is obviously not healthy, and you deserve better.

Take care.