What should I do..?

So I was talking to this guy Derrick for a while, and I liked him a lot but we hadn’t been able to meet up. Every time I was available he wasn’t, and every time he was available I wasn’t. He did try to set up dates with me but it just never worked out. We finally scheduled a date where we were both free, but last minute he said “I can’t hang out tomorrow” and I said “I understand, is everything okay?” And he said “yeah”.. he never mentioned another girl or anything like that. Then two days later (today) I get this message from one of his friends on Facebook.

I’m really hurt that Derrick is talking to someone else but at the same time I respect that he’s only talking to one woman at a time. But I’m really hurt honestly because I liked him a lot. Should I be upset with him that he didn’t tell me himself, talk to his friend or just leave it alone? I kind of feel like Derrick is just throwing his friend at me because he feels bad about it. (And his friend is pretty cute) but I don’t know... what would you do?