Don't just leave... TELL her you aer going to cut the lawn before you leave...

Just keep your distance. SHe's likley going to try to bait you into a fight if she hasn't yet...

Don't even say "you're welcome" with a smile... That baits her to snap back...

Just help her and try to keep YOUR SIDE warm and civil without doing anything to trigger her to snap.

If you keep being nice without even being sarcastically nice she's giong to HATE it and will be even more uncomfortable about divorce...

The lower she gets the more she's going to try to drag you down with her... Just tell her NO... I won't do that and stay civil and kind...

If you can't take it then excuse yourself for twenty mins and go take an emotional break