told me she won't be able to move on for years and doesn't wanna date.
Welcome to women's world. It's confusing af and if we're internalizing their words, sometimes they'll hurt us.
Women can talk all lovely words and it won't mean a thing. This is something that you need to realize first if you're dealing with them.
The sooner you realize that women aren't angels, the more you'll understand of what game you're playing in.
Women can manipulate words and thinking that this way is better for you to not feeling hurt inside,while in reality, it will hurt you in long-term. I call this as women's shi**y logic. The solution is to never take their words seriously. If she doesn't want to to take any action with you, then she is definitely not interested in you. Her engagement will show you what path she's taking.
First love is always hard to forget. It'll even harder to forget if you keep remembering your past experiences with her. Cutting all ties physically (contacts, social media and so on) won't help you much if you are still contacting with her memories with you in your mind regularly.
In order to forget her, whenever the thought of her comes to your mind, immediately fill it with something else. Do this religiously, and she'll soon be gone from your life & mind.