God tests us like the way you're being tested.

The only way to pass this test (and reap the many rewards of passing it) is to be kind to the guy. Be really kind. Say something nice about him to his face. Be cheerful. Wish him a good day. Say nice things about him behind his back. You don't have to feel it, you just have to do it.

Eventually you will break him and he might end up being someone who can help you some day. He might even become your friend.

This is a test. You can pass it or you can fail it. If you fail it, you'll have to take it again, but it will be much harder.

Better to pass it now.

I hope you choose the higher road. If you do, God will help you with it.