I know nothing an internet stranger is going to make you feel any better but it's not your fault your store is understaffed. Hopefully they can find your replacement in the two weeks, if not, not your problem. Please don't think about staying past the two weeks even if they beg you to stay. I agreed to staying until my boss found a replacement before. She was just taking advantage of me. She never had the intentions of finding my replacement. I stayed an extra two months until I realized what was happening and decided not to show up at all.

Best of luck to you.

This is not your problem, this is your SMs problem. They should have anticipated the possibility of you leaving, and be prepared to have the other partners fill in the gaps in the schedule, and be ready to promote someone to fill your place.

The reality is that at starbucks everyone from barista up to DM can and will be replaced quickly whenever there is a need to do so. They'll figure it out and be back to normal operations in a week or 2 at most.