How can I be a better person?

I know I am the worst person in the world. Im a very mean, jealous, competitive person. I realize that I have never had a close friend or a best friend and its because i dont seem capable of loving anyone from deep within. I always look at the bad side of ppl and use that to keep my distance or i just put ppl down. I think I have no social skills--for instance a week ago i interacted with someone in a way i thought was completely friendly but later i found out that person thought i was rude-How could that be? Everyone hates me-including my husband and my parents. Now i feel completely alone. I realize Im never happy for someone if something good happens to them, I dont keep in touch with family members, dont care if they are sick or well. Im just a monster. Ive never done anything wrong to anyone but i know Im just a horrible person and everyone knows that. I think people are starting to see me for the horrible person I am and thats what makes me feel even worse. How can I learn to be nicer to ppl and not come across so mean or condescending?