Am I being selfish?

I have always tried to be a good friend. Give advice to my friends when they are in need, either if it was relationships or stress or depression. But I've never used to speak up about what I felt. I've always felt that maybe my problems were just some childish stuff and it would be selfish from me to throw unto another person. Now my family and I find ourselves in a very difficult situation that has affected us mentally and economically. We have a very promising plan to get out of the situation and at this moment everything seems to be going well. But since this started I've felt so tired and stressed, in nights like this one I tend to cry and ask myself why am I feeling like this. I feel useless, unmotivated and weak. There has been so many changes in my life, but everytime I seemed to adapt to one I get placed in another. And I can't do this anymore. I am so tired of adapting to new situations and having to deal with all the emotional mess that leaves in me by myself. But I can't talk to anyone, because no matter how bad I'm feeling I just don't want to make it worse to somebody else. My parents have been really stressed these days and the last thing they need is a depressed son. My little sister can't have someone so miserable as an example of what her future will look like. And my long-distance best friend, who I secretly love, can't have me (the one she always goes up to get support and advise) demonstrate that I'm actually weak and I don't know what to do anymore. Everytime I feel like something she or anybody else said bothered me I have to keep it in because I feel I would be oversensitive if I showed that something so small like a joke or a comment affected me so badly. I've even reached to the point of having bad thoughts, the "what if I wasn't here" kind of thoughts. And what scares me is the feeling that it might do more harm to others that it would to myself. The thought that my only reason to keep going is because I don't want others to feel sad. And I'm scared of what's going to happen when my hearth runs out of excuses. But I really feel like I'm being selfish, even about my friend who I secretly love, it makes me doubt on myself as if I really love her or I just want her to love me because I don't love myself anymore. I just want someone to hold me like I hold others and tell me that I will be okay, but I feel like I'm selfish and a bad person for even having to ask for something like that. It's painful, but I can't let others feel that pain because of me.