When Stacey was crying that she loved him and he turned round and said "Tough" I think he felt a bit remorseful then but he'd just had enough by that point after all her antics during the evening and after what he'd just said he couldn't exactly turn round and say "Ok I forgive you."
I actually think he reckoned something had gone on between Stacey and Rhys and after everything he went through with his Mum & Dad he couldn't take it.
I think they've both pushed each other to the end of their tethers tbh! Stacey because Bradley's been so wrapped up in his career that he's not really bothered to think or ask her about how she's been feeling after the abortion and Bradley because ever since the abortion he's never been able to do anything right for Stacey when all he wants is to make it up to her and prove he does love her! As I've said before it's 6 of 1 and half a dozen of the other where those two are concerned