Hi OP.
I've stopped and started piano several times over my lifetime and am currently on a big burst of it age 50 and it's going really well. Similar to you I did a lot of work in my teens. My old piano teacher once said that when you go back to it, after six months you'll be back where you were. I've found this to be true. You do have to put the work in during those six months though.
I've done a bit of research into how it all works. Playing the piano is a complex process - there is muscle memory, harmonic memory, didactic memory. If you do it when you're young and your brain is more elastic you make faster progress but also you fire up the bits of your brain that sharpen these processes to a great extent and that doesn't really go away. You just need to tap into it again. You've already done the work.
Start with pieces you love. There must be a few if you played so intensely. Give yourself the time and space to rediscover them. If possible use your original sheet music. If you don't have it try to find the same editions as the ones you learnt from. If you think about when you were playing before there would be a fast constant interaction between what you saw on the score and what your fingers were doing. Having the physical notes in the same place on the page will help to get that connection going again.
Don't start with beginner pieces, there's no point. Start from where you left off, or near to it. It will be difficult at first, but you will rapidly progress.
Interestingly, if you had weak points in a particular piece they will still be weak going back to it even years later. But now is your chance to correct past wrongs!
And don't forget, all that time you've not been playing you've still been listening because music is everywhere. So at some level even when your hands haven't been active all these years your musically trained brain has been receiving and processing music. You may well surprise yourself with what that enables you to do, what fresh ideas it gives you, when you return.