When you did all your best bust still he cheats on you. Never question your self. There is nothing wrong with you. It's not your problem anymore. Don't question your worth where in fact they are the one who is not worthy in the first place.
Don't you ever beg someone's attention. Don't beg for them to stay, you don't deserve a cheater in your life. Do not be desperate if you found out that they easily find the way to replace you, it's not you loss anyway. Someone like cheater is not worthy to keep.
Yes, it hurts that all those happy moments turned out blue. All those things you are wishing to happen, didn't happen. You invested your effort, time and almost your life to this relationship. But still, it's enough it failed you. Don't look for that missing piece. Do not drown yourself to tears and sadness, but instead use this as an inspiration to move on , to heal. It's just temporary.
You deserve someone better, someone who is worthy of your love and care. He's just there, waiting.