Your sorta "past this" now, but one thing you should never really do is worry about much of anything until your CYA is dialed in. Dumping gallons of liquid chlorine in a pool with sky high levels of CYA is just wasting chlorine. Any sort of adjustments, especially when faced with or in the middle of replacing a large percentage of your pool water are going to be wasted time and money. In a situation like that one, you don't start trying to dial in the pool water chemistry until after the water exchange is done and your happy with the CYA readings. Pool stores get a bad rap, because most of them deserve it. I haven't found a single local store yet whose testing equipment or recommended shopping lists are worth a darn. Doesn't mean it isn't possible.... just the ones I've gone too are real duds. Testing my CYA at 0 and yet it's perfectly where I want it at 30 PPM. They have me adding pounds of stablizer powder in their shopping list.... no thanks. You've learned that lesson the hard and expensive way too, though I guess through no fault of your own. Just make sure now that you have stablizer where you want it, that you only add forms of chlorine that do not contain stablizer or you'll soon end up needing to drain pool water again. The trouble free pool method works, because it follows the chemical science and common sense. Chlorine, baking soda and stablizer are all I've ever needed to use in my pool and I'll now be in my 7th season. If it ever turned green, it's because I neglected to maintain a proper FC-CYA ratio. It's happened 3-4 times over the years. I get busy, forget about it for a few days.... once I ran out of cal-hypo not realizing I can just dump bleach in it.... we don't start out as pros! We learn over time! And now, with my TF-100 test kit and the knowledge I've gained here... I run my pool instead of letting it run me!
