Please don't worry yourself over it.
I know that's easier said than done!
This is not exactly wise - but it's hardly uncommon. It happens a fair bit.
As long as you can continue to perform your job well, you are going to be absolutely fine.
Just put it behind you, move on, and DO NOT DO IT AGAIN.
Make a bit of a plan for how you will avoid that. Eg don't drink around him again. Have a script ready in your head for how you'll reply if he ever tries it on again.
I would say that the latter bit is the trickiest. The issue with this sort of thing - and to be clear, this issue can very much arise whether you sleep with the boss or resist their advances - is that ultimately you have to find a way to stay on good terms with your boss while also potentially rejecting them. That can be hard and is something that affects women much more than men, unfortunately.
If he is a decent person, he won't make further advances. If he is a half-decent person, he will respect your saying no to any future advances he makes, and not hold it against you professionally.
But to stress - the above is an issue for anyone whose boss takes an unprofessional interest in them, and is not a situation that specifically results from you sleeping with them... Ie it's a him/boss problem, not your fault.