How to slow things down.

I met this guy on a dating app. The first date was great. He's sweet and I immediately feels comfy around him. While we text, he would call me babe. We only been talking about a month. 
The first date we only kissed but later that night, we webcammed and masturbated together on camera. 
He was in a long term relationship couple months ago and he told me that I shouldn't feel a certain way since it was only months ago.
How to date someone and not become a rebound?