
1) If they don't have an active platonic friendship that isn't hidden from you, then sending her money is weird. 2) "Fantasizing about her"... We need more context. Why did he share this with you and how did that conversation go? 3. Liking posts, can be excusable if they ended on good terms. But if she broke up with him, then he's probably down bad.
I see a possiblity where your feelings are rational and a possibility where your feelings are irrational. But in the scenario where your feelings irrational, it seems to me that there's a communication error where he's not being transparent or constant about how he feels about his ex.