Perhaps instead of "to be an amateur," something more like "to be lackadaisical," or something closer to that.

am·a·teur /ˈamədər,ˈaməˌtər,ˈaməˌCHər/ noun

1. a person who engages in a pursuit, especially a sport, on an unpaid rather than a professional basis. "it takes five years for a top amateur to become a real Tour de France rider"
2. a person who is incompetent or inept at a particular activity. "that bunch of stumbling amateurs"

It is safe to say that ANY beginner, pursuing literally any activity, save some with natural talent, is going to be unpaid / not a professional / inept at said activity. That's how you learn to get better. As Jake the dog says, "sucking at something is the first step towards being sort of good at something."

So while I agree with just about everything you just said, it is quite literally "what it means," even if that is not what it intends to mean.

Wow, that reads as kind of toxic to me. A beginner is by definition an amateur. "No citizen has a right to be a beginner in the matter of physical training." So in other words, if you aren't already good at it, you shouldn't be in the gym being an amateur. Feel like this mentality keeps a lot of people away from the gym.

Why were you so insistent about sharing your/his dirty laundry? Furthermore, if he felt really bad about it, why are you continuing to bring it up and make him relive it? Sounds toxic to me.

Yeah and any belief system that treats women as being worth less because they've had sex is a misogynistic one.

Edit to add: this should go without saying but a woman's value has ZERO percent to do with their vagina

That's not what I said. What I said is a woman's value doesn't diminish based on the number of partners she's had. That's ingrained misogyny speaking.

People don't get "used up." That's some fucking biblical era logic. If anything they gain experience and level up

Hard disagree. Girl was trying to hold OP to a double standard, maintaining friendships with people she's dated while questioning a friendship with someone OP never dated. Good job OP for pointing out double standard. Maybe do it more delicately next time but don't get suckered into accepting double standards.

You're not wrong though. Spoiler alert: it's totally ok to be friends with your... friends. It's ok to be friends with your exes! Nobody here did anything wrong. You (maybe a bit bluntly) pointed out a double standard, which is a good thing! Way to maintain your (totally acceptable and healthy) boundaries, friend! It's dumb as shit to get jealous over exes - they're exes for a reason. It's even more dumb as shit to get jealous over people you kinda liked but never got with as a teenager, because for most people that's a lot of their friend group growing up and many of those friendships carry over to adulthood. I can think of a great many women off the top of my head that I had crushes on in high school and am still tight with in my mid 30s and I'm happy to see them married and having kids. That's just basic emotional maturity. Honestly the only TIFU I see here is "it bothers me to know she's been with others." Like bro, everyone has a history, sex is literally just sex, virginity has no physical metric and even less value, it's just some stupid concept from back when humans knew even less about themselves than we do now (the notion that someone is "tainted" because they have experience is dumb as fuck). Apologize for hurting her feelings but have a serious talk about jealousy and how toxic it is, because if she's afraid of your childhood friends she's not gonna be comfortable with you talking to women in general, and that is toxic as fuck.