Good of you to recognize the danger of resentment. Appears the both of you have a ton of grievances to draw on. I don't know what your mom's resentments will do to her, but yours will drive you back to the bottle if you hang on to them too long.
Be the bigger person and swallow your resentment. Tell your mom you know this was an imposition and how much you appreciate her taking your kids this summer. Replace resentment with gratitude.
And don't drink.