@64Wing - i was going to ask how old you are, but i found a pic you'd posted with Jim Lovell and it seems like you're a relatively young guy (which is a good thing).
I had a five year relationship end in my mid-twenties. It absolutely destroyed me at the time - I 100% thought she was the one. Sometimes one person figures out that it's not right before the other (it was the case for me, and it sounds like, for you as well). Do not blame yourself; and, as hard as it may be, don't blame her either. This pain is temporary but one thing that will stick with you forever is how you react and respond. The character you show.... if there's one thing you can and should do, it's to act honourably in this situation. Be respectful, be at least outwardly empathetic... act in a way that, when you look back in 5, 10, 15 years, you feel proud of yourself for the way that you handled a difficult thing- after all, that's all that you can control in this situation.
Do not look at her social media, turn off any and all contact. If/when you run into her randomly walking out of a Starbucks, it will destroy you for a moment... that's ok. It's going to take you awhile to feel better - in the meantime, make yourself the project. Exercise, eat better, buy some newer clothes, go to therapy (such an important thing - it's an investment in you)... do something you've been wanting to do for awhile but haven't (read more, join a softball team, go to improv classes (assuming you can with COVID), teach yourself to cook....do something to improve you that's fun). These are all things that will make you feel better, will help you meet people and allow you to use this painful time for good.
I ended up meeting the woman I'm married to 15 months after my breakup. She's absolutely the right person; and, despite how i felt at the time, the girl that broke my heart wasn't the right person - she just saw that first.
You will come through this; treat it as a wake-up call and an opportunity to make yourself better. Don't get too down - this is part of life and she has done you a favour, despite it likely not feeling like that right now. There are no winners and losers. Your friends will not think less of you; people have short memories. One step at time, one foot in front of the other, keep moving forward and you'll come out the other side stronger than you ever were before. Good luck and hang in there....