My boyfriend has social anxiety disorder. He won't seek therapy which I have suggested.

My question is, how do I find the balance between 'forcing' him to do what he doesn't want to do, and 'enabling' him by allowing him to bail out of everything. I have anxiety myself, but not social so I understand it to a degree but I have worked on mine so much it's barely noticeable. 

Tonight we are due for a New Years gathering, about 10 max people with some video games, quite casual. He is already panicking and saying he feels ill. Do I say I'll go without him and leave him at home or expect him to go and begin to face his fears? I can't just stay home all the time with him. I have tried being understanding and helping him to rationalise and suggesting we only go for half the time but then he says he doesn't want to ruin the night for me. What he doesn't understand is him not coming also ruins the night for me.

Help!