The moment you see her you realize its time to move on. Everything you use to have and cherish with that guy is now hers. He doesn’t belong to you anymore and really never has. You should not be happy or sad you should feel relief. It is a time for you to get a hold of yourself and move forward. It is time to let go of the guy who is happy with someone else. If you truly care about him you will let him be happy. Even if your relationship was serious or not so, let him be happy with the other girl. You deserve it to yourself to let it go and let yourself free from the heartache. There is no point of being jealous. Make it into a positive situation. Let the other girl win. You will not gain anything.
Most likely time has gone by and he has managed to find her and that’s okay. Maybe you need to be open to someone new and if not being alone is okay. You have thought about her 1,000 times and still try to come up with things that are wrong about her. There is nothing wrong with her. She has beautiful eyes and beautiful hair and she probably is beautiful inside and out. He noticed something in her. They share something in common. You do not know all the details and you should not want to know everything. You should just think of it as a wake up call. It does not mean that your relationship with him was not real it just means it was not strong enough. He wants to be with her for a reason. Do not drive yourself crazy thinking about all the memories and disappointment. He is gone.
Stop thinking there is something wrong with you because he did not want you anymore or moved on too quick. There is nothing wrong with you. You are beautiful and have qualities that one day one guy will be obsessed with, he just isn’t that guy. Do not change or think of ways to be like his new girl. She gives him something that you could not or lack of, that’s the truth. But that’s not a bad or sad thing. You deserve someone who loves you for ALL your qualities. He and you did not work out for a reason.
Stop being jealous of her. And stop wanting him back only because he has moved on faster than you. She did not do anything wrong to you. She obviously saw something like you did one time in him. She makes him happy. She is giving you the moment you need to realize life moves on. There should not be any more heartbreak. He is not your person. If he is he will come back to you in time. Do not make it your personal mission to sabotage their relationship to make yourself feel better. You cannot force love or break another's love.
When you meet the other girl let your heart free. Let go of the past you had with him like he did with you. Be happy, do not hold on to hate and the jealousy. Take the time to realize it is okay to move on; he is not coming back to you. She is not you, and you are not her. Let your heart be open to someone else. Everyone has a soul mate, and everyone should have the chance to find his or hers. If it is meant to be love will come back. When you see her, take one small breath and smile and never think about him again. You should really thank his new girl for giving you so much clarity.