Well, firstly, you have no need to feel guilty. You are a free woman and a grown up and at liberty to date who you like.
Whether it’s too soon only you can say. I know I rushed into dating too soon though. I think I was looking for a distraction from my thoughts and feelings. Those early dates didn’t leave me feeling so great. That said, I them just saw a very old friend regularly as pals for a while (I joined his bubble in lockdown so we would both have company rather than be alone – he was a very supportive friend) and a couple of years on we’re now a couple and set to move in together later this year.
If this is an old friend perhaps you can explain that you’re not ready for anything too much at the moment but enjoy his company if that’s how you’re feeling? It’s okay to have boundaries. And it’s okay to change your mind about things too. Xx