really?

I have finally found someone that I fell head over heels for, I'm happy, and honestly have the man of my dreams in my life. However, I can't help but think of sex and the city--the last episode of the series. It's when Carrie yells at Big for walking back into her life ONLY when she is happy. There is a certain someone that is attempting to walk back into my life just when I am perfectly happy. The last time this person and I hung out, it was toxic, the whole "relationship" was beyond toxic, there was nothing good about it. So why isn't it easy to write this person off as a waste of time? I'm not sure, I feel bad for people that are emotionally hurting. I know I can't fix anything in his life, and I am definitely not giving up the great thing I have in my life, I just wish someone would give me a sign on what to do.