Should I stop taking Spironolactone after my mommy makeover?

Congratulations on having undergone the tummy tuck procedure. Assuming you are doing well, without evidence of dehydration or electrolyte imbalance problems, continuing the diuretic  should not be a problem. As you mentioned, always best to run these types of questions by your plastic surgeon. Best wishes for an outcome that you will be pleased with long-term.

It is important to discuss all medications with your surgeon prior to surgery including prescription, over the counter and any supplements. At twelve days post op it should be fine to have resumed your preoperative medications but you should first clear this with your surgeon. She/He is most familiar with the details of your surgery and how you've been progressing through recovery.

The use of diuretics per se is not a problem. Nevertheless any medication should be cleared with your surgeon prior to the operation. At this point I would discuss the issue with your surgeon and see if he wants to discontinue.