Are they groups of friends or general interest groups? I created a fake profile where I just join groups I'm interested in, and it's worked pretty well. It's just about the only way I use Facebook these days - I only check my "real" profile once every 2-4 weeks for a minute or two to see if I received any messages.

The only downside is some groups won't accept you if you don't have any friends, but there doesn't seem to be many like that.

Along with the groups app, you can get a browser extension to block the news feed, and liberally disable notifications that you don't care about (including email/sms).

try their standalone Groups app

Ah... Thanks! I didn't know this. I wanted the groups feature but don't want to deal with the feed