Is it normal that i can’t forget her?

Not sure if this is a prank post.

Putting aside the matter of infidelity, you're a much older person and an age difference like that can out a major strain on even the best of relationships. What you had sounds like sex, nothing more, even if you felt that there was.
If you're serious then I strongly suggest counselling. It sounds like you'd benefit from getting some things addressed

Wait, is this a song?

you're being played like a fiddle

It was a long time ago. It's in the past. What's the point in thinking about your oh so good memories that happened long ago?

Have you written another post on here about arguing with your wife a lot?

If so, is it possible that because you're experiencing unhappy times in your marriage and not getting along with your wife, your mind is yearning for those better times with another person? You may be just viewing those times through rose colored glasses.

Yes, it's normal to remember your 1st and your great loves in life.

I remember several of mine as well. My wife is my 4th great love in my life - and the most important one presently.

She does know about the previous 3, including their 1st names.

Lol I hope this is a troll. Come on you did wrong, leave your wife if you're still thinking about a girl young enough to be your daughter.

Soon you'll let go of what had happened.

Not always the case but it will happen eventually.