Oh my god, the older you get the more you’ll need to realize that partners WILL have experiences that they enjoyed with other people in the past, that’s just a part of figuring out who you are and what you like as you develop as a person. Be happy that she’s comfortable enough with herself that she’s able to explore herself and understand what she likes. You need to relax, she didn’t do anything wrong and you should apologize for reacting with a “confrontation” and snooping on her private conversations