Hi, and welcome to the forum! You’ve definitely come to the right place to learn to knit. (And $100 knitting lessons? Good grief!)
I’ve also had some splitting problems with Sugar & Cream. One thing that might help you is to try to knit more loosely. It sounds like you’re wedging your needles into the stitches, which is common in new knitters. There’s a helpful article here about loosening up your knitting. (This will also help you avoid stress injuries!)
Other than that, you might also try knitting with wool. Cotton isn’t very elastic, so it’s harder on your hands. The first time I knitted with cotton, it wore me out! Some good inexpensive wools are yarns like Patons Classic Wool, Lion Wool, and Cascade 220.