First, you give no detail, so we do not know what you are scared of. Second, if your fear is because of physical or mental abuse--run, don't walk to the nearest shelter! I lived with an abuser for years, both physical and mental--when he started hitting the children, I got a backbone and filed for divorce. I left with a gun pointed at his head--I was MAD. And tired of his bull.
Third, if it is because you don't want to be alone, honey, being alone is good sometimes for a while and until the right person enters your life. Learn who you are, what you want in a partner, and don't settle for less.
Never look to anyone to make you happy--you be happy for you. Never depend on someone else's backbone to keep you standing tall, you keep you standing tall.
Whatever the reason for your leaving, do it quickly and cleanly, and don't look back!