How do you disconnect from old high school friends?

I wish now that I NEVER went looking for old high school friends online.Now that they are back in my life,I find many of them living in the past,thinking of me as shy little Connie when I'm very ertive now a days,they call me for every little petty problem they have.One asked me to help one of their friends because she is going through the death of her husband in Wisconsin.I live in San Francisco now.I don't know what to do because I soon as I call that person in Wisconsin,she will be calling me all the time because she thinks I'll help.I can't help other people out of every problem.I have some of my own and feel overwhelmed by them alone.I feel like telling that one person why SHE doesn't call the person in Wisconsin.A little bossy huh? I feel put upon,caged in,used,They never help me back at all but expect me to help them I' grew up and have a whole new life now.They live in the past.What can I do to slip away from them without hurting their feelings or making my disappearance all that notecable.Anyone else have this problem?Thanks