As PPs say, no need to feel bad about it. That happens and there's no harm as long as no-one's being cheated on and everyone consented.
But obviously you do feel bad about it, or you wouldn't be here. You say you feel bad for having so little self control. Control over what? Do you generally feel that you shouldn't have sex outside a relationship? That it devalues you as a woman and a person? That you should have gone out with this man for a few dates first? But you have been - you've been talking to him for a month and you already knew each other, you have mutual connections.....
So what's the difference here? If you had been out with him to the pub (or whatever) twice a week for a month, wouldn't you be thinking about sex by now? Or even have done it?
And the guy you slept with. Will you see him again? Is this just a pleasant interlude, or the start of something else? Do you want that? If he wants more of you, then decide how you want things to go. FWB? Relationship?
Are you worried that he will now judge you, ghost you and send you back to where you were (mentally) at the end of your last relationship? If he does that, he's a wanker of the highest order and you're well rid.
Easy to say "chalk it up to experience" but that's the way forward. In fact, that's my advice, chalk it up, decide how you want to be in the future and don't beat yourself up if you do get tempted.
After all, we've all promised ourselves just one chocolate and woken up surrounded by Celebrations wrappers.