I think my ex and I could get back...

I recently ended a two-year relationship because my girlfriend and I couldn’t make it work. It put me through a lot of pain, and I have only just begun to recover. My parents saw what I went through and are convinced that my ex-girlfriend is a bad person, but the truth is we both made mistakes even though we love each other a lot. She and I have been chatting again, in secret, and I have a feeling we will get back together because our mutual attraction is still strong. I don’t know how my parents will react to this if it happens. I don’t want to make them think that I am incapable of making up my mind, and I also want them to accept my decision. What should I do?
Telling them the truth is a good way to start, because all they are basing their opinion on is how you have reacted to the end of your relationship. If you say nothing about what happened, and don’t speak up for your girlfriend, you can’t blame them for thinking the worst of her given that parents are naturally biased towards their children to begin with. This shouldn’t make you come across as frivolous if you can be honest about your feelings, talk about your mistakes, and explain why your girlfriend is still an important part of your life. Your parents want to see you happy, which is understandable, so the effect of this relationship on you will also change how they see it.

How do I know if I should move in with someone or not? My boyfriend thinks it’s a good idea and I am not averse to it, but part of me wonders if this can cause harm to our relationship.
If you are both willing to give it a try and can do it by being honest about what you expect, this shouldn’t cause harm. Honesty and clarity about what you want for this relationship will make all the difference to your future.