I would certainly say you should be on each other's friends lists. I would also say that yes, there will probably be things you don't want each other to read, and that there's nothing wrong with that. Venting where the people you're venting about can't see or hear it can be exceedingly useful, as long as you use it as a tool to organize your thoughts and bring it up more calmly to those people later. If you find yourself wanting to keep a lot of secrets, that's an important thing to know, too.