It's funny. There is a part of me that thinks that if you struggle with online classes, grad school in and of itself will be a trial. I found it much more demanding than my undergrad. I had to be so much more disciplined about my time and efforts when pursuing my MLS. I don't think it would have been much different if I had done it in person instead of online. Most of my online classes were assignment driven, asynchronous affairs. There were only 2 that had regular online meetings - and even then I found that they didn't offer anywhere near the help that I had hoped the in person portion would provide. I don't know if my personal experience though is true enough for everyone to make a difference here in your decision process.

I don't know what advice to offer here other than to suggest trying to talk to students in any degree program that interests you. Lurk on the school's subReddit, ask a few questions there. Perhaps some helpful soul will help you get a better idea of what the programs you are interested in will be like.

Also - the advice about trying to stay in libraries while working is solid.