The holidays can be so hard....
I'd say definitely no drinking at the party. Maybe buy some syrups and play around with soda and ice?....Little party cherries???

It's understandable that your wife feels the way she does when you talk about harming yourself. And it's understandable that you feel the way you do. You both need support, right?--and your son, too. Can you make commitments that are concrete, rather than general? I feel better if someone tells me what they are making a specific commitment to, not just that they'll try. It's clear that you're all trying.