So sorry to hear that happened to you! You put in a lot of time (not to mention the expense) and did not deserve this, that’s for sure.
Did you let the jars touch each other at all? Even after they have cooled it can happen if they touch. Also - older jars that have been used for years will do that. A friend of mine had that trouble after buying a bunch of jars at a garage sale. I always use Ball brand canning jars. As they start to “age” I use them for the freezer.
I have a habit of using the jars for freezing as well and I try to keep them separate because of the temperature differences. I have the ones I use for freezing and the ones I use for canning kept separate. Sure it sounds silly - but I once grabbed a jar I had used in the freezer and it burst in the pot while I was canning.
Make sure you always use new seals for canning; the used ones can go in the freezer. Also - once the jars have sealed I very carefully remove the rings not to break the seals after they cool. In my opinion, by leaving the rings on and trying to tighten them after they cool, you can break the seal.