It sounds like you're not used to winter driving ... as in all cars, no matter if you have winters or all-seasons, you're gonna slip! Unless, of course, you've got chains or studs ... So, as said before - TAKE IT SLOW!!! Pump the brakes ... etc ... If you're on ice, you're on ice, no changing it!
The BEST thing to do is to find an empty parking lot, go out in your Rav4, and PLAY ... practive spinning out, recovering from a slide, stopping in snow/ice, etc ... and HAVE FUN doing it! You'll learn how your car handles, you'll learn how to spin out and make it around a corner when sliding like you were, you can learn alot - you just have to get to know your car in the snow!!
I was sliding like you were once in my old '96 Tercel, but towards a 4-way intersection ... and my light was going from yellow to red, and there was one car at each other direction in the intersection! I couldn't stop, was on glare ice ... I tried EVERYTHING to stop, but NOTHING worked ... pumped the brakes, down-shifted and gave it gas, tried to let the engine slow me down, but NOTHING ... I was going down hill and sliding into a 4-way intersection ... I got to the bottom, turned the wheel, pulled the e-brake up n down (got the back end to slide), Down-shifted, gave it gas and made it PERFECTLY around the corner like I was on pavement ... but I stalled the car (ha!) ... If I hadn't played in parking lots, I'd never know how to do that and save my life!!! GOOD LUCK and HAVE FUN!