Cheesy, why did you say you aren't invited to the grad activities? I thought you were and that you're going? I hope you go.
Regarding the key, yup, sounds pretty suspicious to me. I can see W wanting her privacy, but if you are a part-time caretaker to D, it seems like you would need a key. But if not, give MIL the key and don't expect to get it back. And don't make a big deal out of it. It feels rotten but don't let them know that. And it seems so stupid for them to make up this story about needing the key. They sound like shady characters to me.
Remember, anything you say to MIL goes straight back to W. She is NOT on your side, she's always going to be on her daughter's side, no matter what she says. Remember that and act accordingly. She's a messenger, so control the message.
11/4/15 W revealed EA/2 months later became PA with co-worker Reconciling since late April 2016 Don't give up until it's time, then move on Be patient, strong and kind but never a doormat