FMLA, short term disability and not returning to work.

Hi!

Looking for some advice. I am covered under FMLA in Missouri. I also have short term disability ( which covers 60% for 6-8 weeks- it may even reach up to 10 I cannot remember ) so my question is if I decided to put my notice in after my STD coverage is up and before I technically set foot back into the building do I have to pay my STD benefits back. I know I may need to pay my employer for other small benefits they have paid out for the 12 weeks. Looking for advice. Thanks