Advice please? should I answer?

I was in relationship with someone I absolutely loved despite some blatant red flags. Eventually, he started becoming distant during a time I needed his support most. He did not check in to make sure I'm okay and when I asked him about it and told him it upset me, he said its just something he doesnt do for anyone. I got over it...kind of...built myself up...Im getting better on my own and I havent heard from him in a while. I am still extremely stressed but I can feel myself making progress. Out of the blue, he texts me wanting to find out how long it would take for me to miss him if he did not message me. I'm lost now. I don't know what angle he's coming from. I don't know if this is genuine or if he just wants an ego boost. I feel nervous about replying because if I do and this text was basically for an ego boost/to compare what his current supply is telling him...I'm the one who's going to end up back in a hole crying, but I also fear this is a cry for help as he has been severely depressed in the past. I also feel like I'm supposed to be over this and he expects me to be cool about it and should be able to answer like a logical person. He always praised me for being logical and cool. But I know in the end I'm the one picking up myself while he finds something new to occupy his time. Sigh. I don't know. Was that text an innocent message? Should I reply? I don't even know what to say. I'm numb.