you should be there. we cant avoid everything nasty in relationships. is this plesant? no. are relationships about support even when it isnt so great? yes. You are strong enough to be there for him. You don't have to be a rock, it is ok to have emotions when you are there, but you should be there- especially if he wants you there-- because if you dont go, first of all it makes it look like you dont support him and is that the message you want to send, and secondly you are either in the relationship on a serious level or not, and if you are then you have to step up during the tough times for the other person to support them. whether he says so or not, he needs you.
i am sorry you both are dealing with this. Good Luck