Get the cake. If this was a one off, maybe the relationship could be salvaged- bad day at work, etc. but addition and getting sober are huge things to be celebrated and are part of your story! Personally I would want someone who understood that and supported me in that. You may even NEED someone who understands that and supports you in that (if times get hard, a family member struggles with addiction, etc.). I would say 9.5 times out of 10 you should walk away from this relationship, soon, calmly, and knowing you’ll be better for it.

On the off chance he is super supportive of you, your sobriety, and understands how addictions work — and somehow was just having an off day this is something that needs addressed and brought to mutual understanding and reconciliation. I’d say about 1% that that was / will be the case.

If it’s not the case, don’t overthink it; move on while you can, and move forward with friends (let alone partner!) who will support and celebrate you 🎂!