Sex with someone new after break up. help!

I broke up with my boyfriend of 3 years about 2 months ago. A few weeks later I started talking to a new guy. I get along with him really well but our schedules are basically opposite so we've only hung out twice. We hung out again last night and things got pretty heating and we ended up having sex. It was great and afterwards we spent hours talking.
Being that I was with my ex for 3 years, I feel like I'm in shock that I had sex with someone else. Sort of guilty like I was cheating because my ex has kept trying to make things work.
Am I wrong for having sex with him? I don't just hook up with people, this is out of character for me so I also don't want to have that impression on this new guy