How do you open up to another person after you've been scarred?

I was crazy in love with a guy for three years. All was great for the first 2 years but in the last he got abusive both verbally and physically. I finally had the nerve to leave him and it was great. But now I'm having a hard time with the new guy I'm dating. I can't give him my full heart because I'm afraid of life repeating itself.

How can I get past my fear and give him a chance?