Thanks a lot for your post Sisu. It's very appreciated.
It's good you can encourage your boyfriend to get treatment and you can talk about it.

My ex is aware there's "something wrong" with him, he told me so and clearly expressed the way he could feel lost and confused sometimes.
But he never really explained what made him feel this way, and I have no clue if he got treatment or meds in the past.

Now I've read about PTSD and I'm informed, I know about shut outs, delayed reactions, sleep issues... and it makes sense. I start understanding the behaviour he had and that didn't make any sense to me at first.

After I decided to break up, I sent him an email with info about PTSD.
I felt I had to do so. I told him we trust each other enough, and I hope he knows I care for him so much. I told him I apologize and hope he won't be angry at me if he thinks PTSD doesn't concern him or it's not my business.

He answered he didn't know what PTSD is, and that he would read what I had sent.
Since then no news from him. I'm not really surprised about it.
I wonder what he thought about what he read...I have no clue if it helped him in any way.

Sometimes I wonder if sending him these info about PTSD was not too agressive, and if it was a good thing to do. I kinda feel guilty I didn't act the right way with him.

Now I feel like there's not much more I can say or do...