I had the same thing happen to me about
4-5 years ago. You can look up spondylolisthesis
It is great you were diagnosed so early; I had the MRI first, which only showed a bulging disk, then 3 epidural steroid injections at hospital before back doctor would even SEE me! He diagnosed it with x-rays in several different positions. I was unable to sit AT ALL, or stand still for 3 months. All I could do was lie down or walk. The good news is that most cases will resolve over time without surgery. 2 things that really helped me were hydrotherapy; pool excercises and hanging from "noodles" in the deep end of the pool. Being in the pool really takes the pain away; it is unbelievable. Had to go to a physical therapy place that was located in a gym with a pool for that. The second thing was that after two months of that with much improvement, but a less than total recovery, my PCP sent me to a sports doc who does prolotherapy. He treated the SI ligament at 2-4 week intervals. On my way to the first visit there, I had to travel lying down in the back seat, as I could not sit at all; 2 weeks after 1st prolotherapy injection, I was able to sit to drive myself there and back on the 40 minute trip. Two weeks after that treatment, I was back to figure skating again. It is one of the most painful injuries I have ever dealt with; hopefully, it will resolve soon for you.