Should I mend a broken relationship with this girl or let it be?

There is this girl that I known for 3 years and I been having feelings for her since the day I met her which is sort of sad. I was the first person to ever like her and I still haven't gotten over her. Our friendship has always been rocky because I would get jealous everytime I see her with another guy. We thought we fixed our friendship recently because we started talking to each other again after a year of not talking to each other and seeing each other. So I asked her out and she said NO. I broke down basically because she led me on for a good 2 months before telling me No. I told her that it's alright to just cut ties with each other. She was hesitant at first probably cause she wanted me to stay a friend but she thought it was best too. I tried to cut ties with her the first time last year but she came back into my life. It's been 3 more months now and I still can't move on. I know I'm a pussy and **** cause of it. Was it right for me to just cut ties with her like that even after a 3 year friendship? I sort of regret this but she is with another guy now and it hurts me even more.