Scout gave you some really good advice. Typically LBS feel that if they can diagnose it then they can move on To curing it like cancer. There are not protocols to cure these labels. The only treatments are time and space. Unfortunately if you are correct and it is MLC you are looking at a 5-7 year adventure.
When I look back on my marriage of 17 years, I had 14 really good one and 3 that were not so fun lol. That’s not so bad these days. Unfortunately at midlife people change and not always for the better. The best thing you can do is accept they changed and hope it’s not permanent and realize that there is nothing you can do to control it. Take the focus completely off them and put it on to you and your children.
Know that not matter what you’re going to be fine.