I agree with Ashelen!
RUNNNNNNNN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Good Luck
When in doubt, don't!
Which means don't get involved with the new girl until you sort out that "confused" feeling about the ex. Otherwise, you risk hurting the new girl. Then, you'll have 3 instead of 2 people who could potentially get burned.
If you want to be with the ex; then be with her and put the heartache of the cheating and the break-up in the past. But, if you want to start a new relationship with this new girl that you seem to like, then forget about the ex and never mind about possibly hurting her.
She dumped you... then she was dumped.
I can't imagine you or anyone else hurting her more than she's hurt herself.
Good luck with whatever you decide to do.
Don't walk, RUN, away. This girl is coming back to you because she got rejected now by the guy she cheated on you with?
You deserve better. Give this new girl a try and put the past behind you. Your ex is your ex for a reason, and cheating is a pretty big reason. Don't sell yourself short; you deserve an honest relationship with someone who can treat you with respect...maybe this new girl, maybe not, but certainly doesn't sound possible with your ex. I want to emphasize though..take it slow with the new girl. you're clearly still hurting from your last relationship and rebounds rarely work...so give this new relationship time to blossom and grow without getting serious too soon, or you will be carrying too much baggage for it to work.
best of luck.