This is kind of hard to explain but I think I'm jealous of my sister feeling bad if that makes sense?

I have had depression and anxiety problems for years and I feel like its all I am sometimes as my family treats me differently to my sister because of it

She is having a hard time at the minute, she hates college and her boyfriend has split up with her and she is really down

I do feel sad for her but I also think what about me???, just cause I feel like that every day doesn't mean it gets any easier and I feel forgotton

Now I feel bad because she is my sister and I shouldn't feel like like this but I do . But if the depressed girl is all I am (which is how I'm treated sometimes) and I'm not the only one now, who am I?

Am I a bad person?
Why do I feel like this?
Why am I so selfish?

Aaagh, sorry for the rant, I'm just really confused