Am I just cruel or what???

That guy called again. Sighs. After I especially told him to NEVER call me again. He just wants me to listen to his problems. He needs just a friend. Maybe it's mean of me but I feel if I do call him back, he'll see it as encouragement and keep on calling afterwards. I can't handle some else's problems and stresses. I have more than enough of my own in life. One thing I know about myself is to limit my stress as much as possible. My job, caring for my daughter, worrying over bills, and just day to day living is all the stress I can handle. Perhaps I'm cruel but I can't worry about someone else's truck breaking down, their not being able to pay rent, or whatever else it may be. I just can't. My heart would break because I could not help them financially or give them what they deserve, someone who really can listen without it bothering them. I can't do that. I have too much empathy for others so I have to limit myself. There are days when I feel like I'm sinking on the threshold of some bottomless pit and just ONE more thing will topple me over. I don't need it. I don't want it. I can't do it. I'm so heartless...sighs.