Why am I being charged like a criminal when I was hit in the rear end

I was rear ended as I was making a left hand turn. I had a passenger who left the scene. They caught up with her and then came to the hospital threatening to arrest me, highway patrol had 2 drug test in his hands asking me which one I wanted to take. Due to his suspicious behavior I refused. He told me outright that I would fail it. He left and came back with 2 no seat belt tickets never asking if I had one on. I told everyone that asked yes I had one on. Driving with a suspended license which I did not know because I never received a letter. Driving Under the Influence because I refused the test.