I just had an umbilical hernia repair with mesh last monday 2/17. I just took a pregnancy test today and it was positive. Would it be safe to take an abortion pill?

Abortion pill. Itself will probably have little or no effect on healing of your umbilical hernia. If it induces repeated retching and vomiting, it will place stress on suture lines so protect it with a pillow.
Dilemma. Usually one would wait for at least 6 weeks after your type of repair to put stress on the abdomen and thus you would have to weigh the risk not aborting earlier vs the potential tear of the recent repair. Although the risk of a tear from an early abortion is likely low, this is a difficult decision and you should consult the surgeon who did the surgery re. This asap.