Most people in my life disconnected from me following my s/s attempt as well. I chose to disconnect from others who were unhealthy for me to be around. It sounds like you had a rougher experience with that than I did in that regard.

Even though that experience was so devastating for you, that does not mean that you owe MC anything, especially not cat sitting. That is silly. Don't let her tug on your heart strings, and try to make you feel guilty.
You tried to get her help, and she chose to seek alternative means of "care" and the the support of other friends instead. She is not alone.

It is clear that you would be better off disconnecting from MC and the rest of that group entirely. Your interactions with them have been very detrimental to your mental health. You have to stop letting them draw you back in...

It may be useful for you to go back and read some of your previous posts so you can see just how much your interactions with these women have effected you. (((HUGS)))