Can the cops charge me even if it's not mine?

At least 6 months ago, I was in my bathroom so I couldn't see what the person in the back apartment was doing as they told me that the police were looking around for someone but weren't coming in to my apartment. I saw in my security cameras that police are still outside. I decided to let them see no one was in my apartment so they would leave. As I showed them to the basement stairs, one cop found a glass pipe on the foot stool next to my bed. It wasn't mine, and I said so. He no longer wanted to look for that person. I felt set up! The cop went outside. In tears, I told people in the kitchen about the pipe. Then the person who had come in without knocking told me that they had hidden the pipe under my pillow. When the cop came back in, I told him what had happened. Then he wanted me to tell him whose pipe it was. I refused. I offered to show the police my security DVR footage. The same cop who saw the pipe said for me to hand him the small bag lying on my bed. I did. The cop asked the other cop if she thought there was enough to test for meth in the bag and she said yes. I couldn't see anything in there. I told the cop that wasn't mine either. He asked whose then. My ex-boyfriend had those kind of bags, so I said maybe him, but I wouldn't give his name. The cop wrote down a telephone number. He said that I had one day to call with names. Issues: I only gave permission to look for a person, I was not read my rights nor was I arrested, I was not given an inventory of the items seized nor was anything tested in front of me. I never did call that cop. At least 6 months later, a sheriff came to my door and served me with charges of possession of methamphetamine. The paperwork says I have to go to the jail prior to my court date and be booked and released or I'll be taken into custody on my court day for booking purposes. The person who hid the pipe/bag says they will testify it was them. I will only let them if RCW 10.52.090 means they won't get in trouble for incriminating.