As to whether to take her back or not, you are the only one who can answer that. One thing I have learned over the years is that even though you always intend for "forever" to mean just that it often isn't. What you go for when you're 16 is going to be much different than what attracts you when you're 25. But who knows? Some people get it right the first time and are happy till death do you part. I know I certainly wasn't one of those!
People do really ****** things to other people all the time, that's the reality. Love makes you ignore warning signs and common sense, no shame in it, we've all fallen victim to it at least once. Or at least I hope we have.
The best advice I can give you is do what makes you happy. But be prepared to live with the concequences. Sometimes it's better to sacrifice short term happiness to be better off in the long run. But you have the luxury of being young right now, you can afford to make mistakes that us old folks can't anymore
Keep your chin up and don't take any crap that you don't have to.