All I can really say is that I strongly relate to every last one of your sentiments and that good friends have told me precisely the same thing that your friend told you.
Personally speaking, the fact that you immediately apologised to the victim involved marks you out as different to the youtube abusers, many of whom have either denied the harm they caused or just outright appealed to their fans for sympathy.
Also, while abuse may be abuse, there are degrees of harm, as reflected by our criminal code. There is no possible way you would serve legal time for what you did. You are not a rapist. You did something stupid, but you haven't destroyed someone's life.
Furthermore, the sad fact is that a lot of people have done something similar when young and will never self-identify as abusers. Even just thinking about things that have have been done to me (as a white straight hella privileged guy!) I've had my kilt lifted up by strangers in the street; had my nipple squeezed by a guy making homophobic comments because I was wearing a pink t-shirt; had a bunch of blokes hold my head forcibly in place to make me inhale poppers; had my butt grabbed etc. And I'm entirely sure that all these people saw what they did as just a laugh, which they had forgotten about before the day was out.
If you look at Struckman-Johnson's scary but important study: 'Tactics of sexual coercion: when men and women won't take no for an answer' (2003) they found that 40% of men and 26% of women admitted to having previously made 'persistent attempts to have sexual contact with someone who has already refused'.
Now, the first important thing to take away from this is that the majority of men and women *haven't* committed sexual abuse... i.e. such behaviour isn't normal and even if it was it still wouldn't be acceptable.
But it is widespread. And I can't help but thinking that the insistence that sexual abuse is monstrously unforgivable and that abusers should be tortured to death etc. hides an anxiety on the part of the public that maybe they too have acted abusively in the past.
It takes a certain amount of strength to accept that you have acted abusively. I think this has marked a significant turning point in your life. I believe you will educate others about consent and how it is possible to believe something in 'theory' without having truly internalised it.
Furthermore, otherwise sensible, progressive bloggers, especially feminists, have a tendency to claim that women virtually never assault men, that such incidents are microscopically small. Studies like Stuckman-Johnson's suggest this is not the case. Definitely more men than women commit such acts, but the amount of women who have committed assault is not negligible.
I honestly think you can make a change. I believe that about myself and so I believe that about you. In many ways I think you are now less likely to sexually assault someone than many people who say that "all rapists should be killed" and never think they have the potential to abuse someone. That kind of cognitive dissonance is ugly and at least you are free of it.
As I said before, you are 17 (unless you have now turned 18). You were still a child when you committed this act and your brain is still maturing. You are definitely not "stuck" and I honestly think that the horror and shame you have felt about your actions will have rewired your brain to ensure you never do anything similar.
At the end of the day, what you did was wrong, but it wasn't monstrously bad. If it were a scene in a film people would shake their heads or feel annoyed, but they wouldn't be desperately averting their eyes or crying. You wouldn't be making any Top 100 'Most Shocking Films' lists. What you did was crappy. That's all. Worth learning from, but certainly not worth beating yourself up forever over.

Finally, I have spent a lot of the last 8 years believing I don't deserve romantic relationships and this has essentially led to me alienating anyone romantically interested in me by telling them this repeatedly and fixating on the past. It hasn't be useful and it hasn't been morally good. It's easier said than done, but once you have told a prospective partner about what you did, you can no longer tell them not to love you. They can make their own moral choice. You totally have the right to be forgiven, but not to tell other people that they aren't allowed to forgive you! Accepting love into your heart will always do more good than harm.