I need Help. My friend is in denial he is using cocaine.

Ok. Now i told him i thought he was using coke because of the way hes been acting lately and he basically flipped on me and told me i crossed the line by making that accusation. He does smoke weed and he does do pills like Oxycontin and Percocet. Here is why i think that he is doing cocaine. He hung out with this friend for the first time in a long time and the last time they hung out they did coke together and thats when my friend said he would never touch it again cuz it almost killed him. He usually takes 2 bathroom trips to do oxy or 1 at work now hes taking 7 or more. Hes been very irritable and hard to talk to. When we went out he said he had to pee at wawa. Then we drove for 20 minutes and he had to pee at wawa again. He said that im full of **** and that he doesnt need to explain himself to me and that hes not doing coke and hes pissed i made that accusation