My partner is currently going through a divorce. What the hell do I do?
That question is probably best posed to your partner. Ask them what they need from you to get through this tough time. Maybe they need patience on your part and an acceptance that you'll see less of them while they hunker down and deal with this. Maybe they need a soft shoulder and someone to vent to. Maybe they need cheerful, upbeat distractions from someone who isn't involved and doesn't need to talk constantly about the divorce logistics.
You also need to make sure you're getting your needs met during this high-stress time. Your partner probably won't be able to do a bunch of emotional labor for you, so you'll need to find somewhere to 'dump out' while you 'comfort in.' Friends, a therapist, a hobby, other partners - make sure you've got outlets as well.