Hi SMK
Lots of my posts have been removed lately asnim not suppose to talk about myself apparently so all I can day is your brother had a similar background to me, and also seems to be in a spot I was.
Addiction stems from many different things and also manifests itself in many different ways – for some people its drugs, alcohol others gambling, sex, spending, eating – it can be anything really.
Additionally he has the PTSD which is going to make things even more complicated for him as that isnt an easy thing to live with at all.
You cant help him unfortunately, but the good news is that if he is ready to get help there is a ton out there you just have to be ready and willing.
A good start is a chat with a GP as addiction is physical and mental and we end up doing all sorts to our health.
He could also speak to a drug counsellor – lots if them operate by zoom or Skype right now.
He can also use AA or NA meetings which will be full of people with similar issues, backgrounds etc. They are also on zoom and he could sit in and observe and see if its helpful in any way at all and perhaps focus on similarities not differences? It’s free, anonymous and very supportive. There are meetings 247 as well all he needs is a zoom account