I'm tired of being the strong friend
In what way are you tired about being a strong friend?
The others always depend on me for too much stuff
Your friends probably don't realize that they are irritating you by asking for so many favors.  It's fine to get tired of taking care of everybody else, but don't cut them off completely.  Just say that you can't help at times, and ask them for help at other times so that they will not be too dependent.
I'm not going to do that. It's their problem for being annoying.
But if you just communicate with them then you could avoid this whole situation I think.