I'm glad your husband is going to these visits. Make sure your MIL signs something (assuming she's willing) that the doctor can share info with your husband when your MIL is not there.
If she's worse now, you had to question what caused the change. Menopause/hormonal changes? Another condition? Problems with the boyfriend (not sure if he's just "not helpful" or if he's part of the problem, or if he's new vs. a long-standing relationship)? Other meds in the way?
I'd say to look at whether she is changing meds too often, or not enough, if she is taking them as directed, and if she's getting the right therapy. I took meds for years and did therapy off and on, but what got rid of my depression (at least to the point where I don't need meds) was adding in additional nutrients. I didn't have the anxiety piece that your MIL has, but 2 colleagues of mine did have that, and we did the same thing to get rid of the problem. It's not an overnight fix, but then neither are the meds. I've been med-free for years now - still have some ups and downs but when I have a tough day I just add more of the same food-based supplement (because it's food, there's no risk of overdose). Since then, there's been even more work/research on gene expression (genes mis-firing and causing all kinds of imbalances, both physical and chemical/emotional) and also non-medical approaches to stress and fatigue. I'm guessing fatigue is a huge side effect of your MIL's depression, but it can also have a causative role. There are a lot of free seminars in the area as well as nationwide, which is where I got a lot of my info and my success stories from others.