Is it embarrassing to tell a friend you're upset about something that they did last summer?

Well he said he'd help with something but didn't keep his word nor he said he can't help, in fact I know he believes if he helps it'd ruin his image or whatever which is dumb and hypocritical if you see the way he lives his life and that alone is fukd up. My mind is screaming at me to just forget it.

P.s I already told him I'm upset about something but I didn't say anything else, he asked me for details but I said it doesn't matter.

I know I'll hurt myself if I ever speak about it because I know the outcome; I'd just embarrass myself again.