Traumatic experience and lack of empathy or sympathy

Background : me 26f my partner 29m been together almost 3 years , live together 2. He was out of the military by the time I met him. He has ptsd (he admits it) but won't get help and trys to self medicate with alcohol. I also feel he's depressed but I realized overall he's just generally a negative person.. nothing is ever good enough, nothing is also never his fault or is worse than what he's been through, any slight issue then his world is tumbling down, ex. life ends when a soda is spilled. Hes very reactive to things and then the next day feels like an idiot.

But back to my point.. I witnessed a horrific car accident yesterday. Long story short , I don't want to go into details .. but I ran to help as I was the car behind it. It wasn't good.. and the things I saw were a first for me.. what I saw and went through were very traumatic.. and yes I have set myself up an appointment with a therapist. But I feel like my bf has literally no sympathy or empathy for me.. like he feels like yesterday was just another typical day for me. It wasn't and I can't unsee the things I saw.. I finally said something to him about being dismissive to everything that happened and my feelings. And he tried to instantly turn it around to be about him. I told him how the things I saw were traumatizing and he said "I'm glad you saw that so maybe you can cut me some slack because of everything I've seen" (meaning the military). I walked away and separated because that's utterly disgusting to me.. I would never wish for anybody to see the things I saw and or feel the way I do.. especially not to the person I "love". If I ever needed him most it would be in this time..