Sounds like you may also want to have DS start calendaring his events. If it's not on the calendar, he doesn't go. And stand firm on this. It is not right for you to drop your plans because he neglected to tell you about an event. My 5th grade students can handle doing this. I post upcoming events, they write them in their planners. At the beginning you'll need to remind him, "Hey, have you put your events on the calendar this week?"

Start scheduling your time. Tell your MIL that beginning x day, you are no longer available between 8 - 10 am or whatever time it is that is best for you to work out. AND stick to your guns.

You cannot be there to take care of your loved ones, if you don't take care of yourself first.

V.