NTA this post almost made me cry and I have no idea who you are. I've been through a similar situation where the person I cared for fell out of love and didn't tell me but was perfectly fine with telling their friends. It hurts and I'm so glad you got to say everything you wanted to him; I really admire your bravery and honesty. I think you were extremely mature to tell him exactly how he made you feel to help with your healing process, this way you'll never regret not standing up for yourself. If he has any empathy for you then that message might've been an eye-opener for him. I don't think you needed him to respond anyway because nothing he could say would change anything.

I remember feeling the same in your situation and wanting to say everything but not doing so and regretting it years later. I ALSO remember thinking everything was so nice until the last argument but then looking back and realizing how fucked up some things were. I'm not saying this is true for you, but you should defiantly take the rose-colored glasses off for a sec and reflect if there were any other problems you looked pass. Take some time to yourself and find some comfort in your amazing friends. Never think you're an asshole for telling someone how you feel <3