I'm a 22 year old guy and I hang out a 16 year old girl, is that weird?

no its not weird that you are hanging out with her becaus eof your assertion of brother/sister love. But she has a crush on you, that won't change, and she is the only girl your around right now. Let's put the peices together where at one point in time you didnt question the friendship, now you wanna know if its weird, she mature for her age, that is an emotional assessment and the fact that you made the assessent means you may also be toying with the idea of " shes a nice girl, but realistically honey if you don't watch it you will accidentally be coming through the door and she oops ! i just got out the shower sorry with naked long legs and half her booty hanging out with a linger. Girls with crushes are crafty.