I was in the same situation as you OP only difference is that I wasn’t smart enough to make the decision to end it, which came back around and bit me the ass I was already invested into her somewhat emotionally that I didn’t want the break up and she went back to her ex or I should say came back in the picture.

Looking back at at my experience one thing I learned through out my years is that it shouldn’t be such a chore to try to keep someone that’s already in a relationship with you.

As the saying goes ‘you can’t force someone to love you or want you, but one day you’ll make them realize what they lost’

Your maturity is admirable.