Brake piston problem

While changing the rear brake pads on my 2001 Chevy Tahoe(96320 miles) the drivers side went well, but on the passengers side I didn't compress the pistons together. As I compressed the top piston, the bottom one extended and the boot swelled. As I compressed the bottom piston, it began to leak and the boot was not retracting well. Now the piston is compressed and the boot is not seated properly and I have no idea what to do next. Do I have to replace the whole housing that holds the 2 pistons, which would mean bleeding the brakes, which I'm nervous about. I'd appreciate any advice, as the truck is sitting in my garage until I figure out what to do next.
Also, what is the best repair manual to get?
Thanks so much for any help!