Dealing With Loved One Who Is Very Depressed. He Insists

Dealing with loved one who is very depressed. He insists that it is "situational depression" due to his being pretty much disabled due to severe ulcerative colitis. He will not see a psych because he insists that they will try to give him an ssri or ssni and he flatly refuses to take it. He is being given lamotrigine right now as we convinced him that it may help calm his GI contractions, which his MD believes to be nerve-related/anxiety related. That is the only way he agreed to take it. He was told NOT to read any info on it online (because we didn't want him to see that it is used in Bipolar pts. He is currently up to 75 mg and there has been no noticeable change in his mental status. He is a former marine and the UC has debilitated him such that he can no longer workout (he was once very muscular and he gets his self worth from that). He will not even leave his home, saying his stomach will not allow him to. However, we notice that he isn't sprinting to the bathroom as much. He is on Remicaid (after years of swearing he'd never agree to a biologic)) and HE says it isn't helping (but it has cleared up his psoriasis). I think it has helped, but he would argue vehemently. He takes oxycodone and valium, because he says it binds the mu receptors and helps dry up his GI tract, where as in people with normal GI tracts, it would cause constipation. He is difficult to be around, but he needs to be around people. Suggestions. A short course of Lyrica really made him hypomanic, but put a great deal of fat on him and he refuses to take it now. But he did say that he wishes he could be that "happy" again. Suggestions?
Signed,
A Weary friend...