Am I just lonely?

My ex/son's dad and I have been split for a few years now. Lately I've been really bummed with life and thinking about him. Mostly because he is still my friend and the only one I want to be around, the only one who listens, who cares, who is supportive and accepting. He still annoys the shit out of me, but life with him wasn't all that bad. I don't dare say a word because I wonder if I'm just lonely and I trust him. On the other hand, I'm lonely and I trust him... I'm so confused why I feel this way about him.