Vetran with PTSD, gun laws?

I'm an iraqi vetran who has been diagnosed with ptsd. I served four years as an infantryman in the army, i recieved an honorable discharge. I've heard a lot of different things about owning and purchasing firearms once youve been diagnosed with ptsd. Does this mean i cant purchase any more guns???? Could someone please set the record strait for me... and i live in washington state, if that helps. Thanks.