Not what you want to hear. To do it right you need cut it out and cut beyond then mud tape seams, use mesh not paper tape. Its always easier by going bigger piece, fyi. Use a sealant on patch and wall. Try to match paint with washable paint. It's not a fun job by far. Or you can go to depot and get a sheet of acrylic drill some holes and screw it to wall to protect it being damaged anymore in hopes it will dry out, but once sheetrock gets damp it will get crumbly and moldy and will spread. I drywall on the side, I love it. Just finished the hideaway bathroom over my garage, total tear out and replace with new floor. Sorry for being Debby downer.