Protecting your sobriety is good for BOTH of you. I'm pretty sure that if he understands how much of a risk you would be taking by going, then he wouldn't want you to chance it.
Making the decision to protect your sobriety is NOT selfish. I would even go as far as to say that if, once you have explained things to him, he puts a drink and drugs fuelled party before your sobriety he is not the rock you believe him to be.
Please. Stay home. x