Most of my friends come to me for some adverse, some about there Jobs, marriages, families, etc. Am i selfish?

Am 34 yrs, my star sign is cancer, now like i said above most of my friends,( female friends) come to me with there problems, even with some of those problems i would not expect them to talk about or share with me and yet they do, and in most cases, from the looks on there faces, ln the first few minutes of talking to them, i would ask them to talk some time and think about what they are about share with me or talk to me about. But them they will all aways tell me its ok, that they feel free and better after talking to me. And they will call me to say thanks for my adverse, and how help full it was to them, and they will show up on my door with cakes etc, trying to tell me thanks and how talking to me have made changes in there lives, Now, l in the Other hand can not talk to them or any other person about my issues, and i do have my own problems. ( and my friends think i have all together, if i can give them some great adverse i must have answers to my problems.) but the truth is that i don't, l just break down and cry some times on my own with out them knowing it. Am i selfish? or should i just tell them to leave me alone.