I think that you had your chance 3 yrs ago and blew it. You cheated, and then realized the grass wasn't so green on the other side so tried to make it up by buying her flowers etc. She was touched, but obviously not enough to trust you again. That is probably why nothing became of it.

She has obviously moved on seeing as she has a bf now. So, you need to move on as well and learn not to repeat the same mistake again. Next time you get bored or fustrated with a relationship, maybe it would be best to talk things through or try to work things out rather then to cheat.
This should also make you realize that theres only so much that money can buy and you can't buy someone's trust and affection.

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Appreciate the good times and learn from the bad times....