What do you think about my feelings towards this predicament?

I’m not going to go entirely in depth, so if you feel there’s something I should have mentioned just let me know. We’ve known each other for four years and when he first saw me he was instantly attracted to me and pursued me. As we got to know one another our feelings became mutual, but due to some past issues, when he suggested we go further than friendship, I declined. It took him awhile to get over it but he did and moved on with a relationship here and there. When we would hang out with a group of friends I guess you can say the “sparks” were still there but we never acted upon them. Time went on and I saw him less and less, especially when he got with a girl I worked with. They ended up going out for a year and a half. She ended it and currently has a new boyfriend. It’s been about five months since they broke up. Long story short, he ended up confessing to me once again. We talked about how we always liked one another but the only difference is I was never in a serious relationship. He assures me that nothing will happen between them (cause she’s with someone else) and admits he still loves her but his feelings for me have always been there. They’re just friends he says. It hurts knowing that if she wanted to get back with him, I would be tossed aside (he never said that but I know). Should I ignore this feeling and give us a chance?