1999 Acura CL Gear Slipping

I have a 1999 Acura CL. I've only had it for 3 weeks and it used to drive perfectly. Last night, the car stopped going into reverse. After a few tries, I got it to reverse and then I couldn't move it forward. The car revved real hard as if it was still in neutral. Eventually, it started to move but it jerked so hard that it was like someone learning to drive a car with a manual transmission. It was very dangerous because it would stall every time I had to stop at a light and then try to take off. I escaped a couple rear end collisions and came real close to a front end collision trying to turn left when the transmission failed to go into second gear and I was stuck in the path of oncoming traffic. What should I do? Have I just wasted my money on a lemon?