I've been in a similar situation. 10 years but we could never agree on kids. I think there are a couple things you need to figure out before you decide what to do.

First is deciding if you can get past the jealousy. Despite understanding why her being with someone else is hard to get over and can hurt, it really isn't her job to placate your romantic feelings anymore. You were both really young when you started dating, and you both didn't get a lot of time to see what's out there and really know what you need in life. It's the time in life when you're having the world open up and you see the clock ticking. During this more options were closing, she was having to decide to disconnect with other people and the experiences populated areas bring. For you two to work again, you have to drop all the jealousy and it can't be held against her. Some couples recover from this situation because they learned that after exploring, they still want to be together. She didn't cheat, she explored when given the opportunity at a time she was also trying to figure things out. She probably felt alone, and nervous about what to do next in life. If you don't need exploring yourself, you then need to think about the next big issue.

Having different life goals is huge. In my relationship, we decided those goals could never line up and that we shouldn't stay together even though we still loved each other. It was hard, but there are plenty of other people in my life I love and there was no need to force a romantic situation if it made either of us disappointed with our futures. We didn't need to trap each other there. If you don't find a reasonable compromise that you're both ok with now, you're not going to magically find one if you get back together.

Being alone sucks, but it's temporary. You're still young enough for dating to not be a complete nightmare, so you both don't have to base a relationship on being lonely. I'm a bit older than you and I ended up finding someone who fits my life goals. She's basically the partner I would create if I had the option. I would've lost that and continued an unhealthy relationship if my previous relationship picked back up, and that would've been bad for both of us. If you love this girl, you should also want what's best for her too. If you two don't match up, and if the sacrifices are too large, it seems to make the most sense to keep separated. If you both are still in love to the point where you're able to make big sacrifices for each other, and understand and forgive what was done in the interim, then maybe it's worth further conversation. No one here will know what's best for you two, so be open for communication and finding out your hard boundaries and deciding what that means long term for your relationship.

Good luck, it is definitely a difficult situation.

My city still has them. They're pretty widely used, but I think we're a good scenario for them. Our sidewalks aren't cramped, we're a very spread out city, and our public transit isn't stellar.

You only really need about a 3rd of the population to control things. These far right extremists are all testing the waters on how far they can go, and unfortunately the supreme court is corrupted to the point they're starting to tear down our legal system. There is no accountability. Lower levels of government can strong arm their opponents out, enact illegal legislation, and rig it so they'll never lose. It's straight up fascism. It's gotten so extreme because they're reaching the tipping point of either being ousted or taking over full rule of the country. I'm desperately hoping the demographics are changing fast enough, and that people are seeing the catastrophy unfettered capitalism and greed brings, but it's a fight that's close enough to be very scary.