Wow, I read the first half of this thread a few days ago, purely out of interest, and since then...shit got real. I don't really have anything to add that others haven't except this: part of how I knew my husband was going to be my husband is because he fell in love with my dog. He didn't meet her for a while because we were in school, so she was with my parents. He didn't like small dogs (she's a smallish spaniel) and was clearly reticent about her when we decided to move out of the dorms and live together. I made it clear, love me, love my dog, and that she'd be moving in with us. Well, within a week the two of them had fallen so hard for each other, and I haven't had any worries since.
If he didn't love my dog, I'm not certain our relationship would have lasted, and that's without the idea of abuse to my dog, either. I don't care if your guy was in a snit or a rage or whatever, there is NO excuse for that behavior in a grown adult. Even my 2-year-old knows better than that.
Another consideration is that there is nothing to prevent this guy from abusing your dog when you're not around. If he'll do it in front of you, you'd better believe he'll do it (and possibly worse) when you're not around. How awful would you feel if you later found out that he'd been mistreating your dog behind your back? Would you still love him?
Yes, it sucks to lose someone you love. But, realistically, he was trying to force you to lose your dog, and I bet you've loved her for a lot longer. Don't let him get to you. You, and your dog, deserve someone better. Good luck.