I was in the same situation. Except I was the one who ended things with my boyfriend and began seeing a great guy. 2 months later, I found myself texting my ex, saying how much I loved and missed him while I was cuddling with new boy. That was my red flag. Once I started talking to my ex and things felt like they were starting back up, I immediately broke it off with new boy and slowly went back with the ex. I do not regret my decision whatsoever. However, I must tell you, getting back together is HARD. Harder than the relationship you had before. But if your heart is telling you to that you love her, go for it! And with new girl, don’t feel bad because she deserves a guy who is dedicated to her and wouldn’t even question going back to his ex. Also, I don’t know your situation and what you ex did to you, but I know I am thankful everyday that my ex took me back, because I realized that I was making a huge mistake by not being with him. But if you do want the ex back, definitely end it right away with new girl and take it slow when getting back with the ex and feel things out first. Good luck!