It's been 6 months and husband is still in "severe pain"

I'm so worried about my husband right now. 6 months ago my husband and step son were hit by a semi. My step son (17) died on impact. I have no idea how my husband survived. My husband has been going through physical therapy because he was in a wheelchair for a bit. The doctor prescribed him oxycodone for pain and my husband is walking now but he walks with a cane. He keeps saying he's in such severe pain and I think because of how severe the car accident was that the doctors believe him and keep refilling his prescription but he does is take the pills and sits on the couch all day. Also he will not talk about my step son. My husband has his son at 15 they were always close. He was one of those parents that was open minded. My step son told his dad everything from his sex life, to break up, to questioning his sexuality. Every single thing. So for them to be that close to my husband completely avoiding talking about him and keep getting a refill on oxycodone I'm concerned. I subjected that maybe we try Tylenol or Ibuprofen. But he says he doesn't think they will be strong enough. I'm not trying to say he's lying about his pain but I'm scared he's getting addicted to the pain killers and avoiding his feelings. When he looked at his sons body he said nothing and that they're going to cremate him. The cremated ashes are in my step sons room and he won't step foot in there. I'm not trying to be an insensitive wife and say my husband isn't actually in severe pain but it's been 6 months. He's walking. I feel like we can move to non additive pain killers.