Maybe she thought it would help to bring someone new to distract you,
One of my all time best friends, met me a few days after my mother funeral, I was in the middle of a complicated split up with my son's father, and was not in a good place,
I had no ability to put on niceties, and my lodger turned up with this woman, she responded to my dark humour, and after my obvious annoyance at her being in my space, she and I ended talking for hours, lodger went to the pub then bed.
she was sent by universe, twenty years later I am so thankful she is in my life, I think she met me at a very dark moment, so from that point on I knew she was not just a fair weather person, you do need tena lady pants to spend any time with her, she could make you laugh at your own funeral.
I bet your friend has told her you are having a tough time and is hoping her SiL will be useful, it maybe ill judged but she might be great.