Is it wrong to want to date him?

To cut a long story short, me and my ex split up just over a month ago, we were only together for 2 months and the break-up was pretty mutual and I thought we ended things on okay terms. Basically, the first time I met his friends was his friend's house party, me and my ex both got very drunk and I started talking to one of his close friends a lot. My ex kept disappearing and talking to lots of different people but I ended up spending most of the party talking to his close friend, his other friends were making jokes about us about how friendly we were with each other so they must have noticed how well we got along, there did appear to be some chemistry there between us.

I was happy with my ex, but I couldn't help thinking about his friend every now and then, I hung out with his friends again we all went for a meal together and I was pleased to see his friend again, but things with my ex seemed to be getting worse before we eventually decided to split up.

Since this, I have been thinking about his friend more, I know it is wrong and I would hate it if it was the other way around and my ex started dating one of my close friends but I can't help my feelings. Me and my ex haven't spoke since we split up.

Should I just avoid this guy and find someone else or should I go with my feelings and see what happens?