first off, i think that you should go and see your ex because the bond as friends that you have obtained seems to be strong. secondly, you still feel for your ex..that is a quite common issue. everyone leaves a peice of them with each passing relationship and there will always be a place where he will have inside of your heart.
as for the confidence part... hrmm.. i would just say that you will have to remain fairly calm. keep in mind that you also have a bf, and that both of you have moved on from the past of your life. meet his gf and try to engage her too. when i meet my ex's bfs.. it's not really a big thing because i'm glad that they are happy together. raverboy
...this is just my perspective on the situation...