Nah, I think that opening can lead into the same conversation, or a similar on.

LW: Arghh! My mom wants me to call her again and it's driving me round the bend!

SS: Don't call her back! Set a boundary!

LW: takes a breath Nah, I just needeed to wave my arms a bit and blow off frustration. She does call me too much but I've thought about it and it's not to the level where I need to set a hard boundary/stop talking to her/whatever.

SS: But you talk about what a pain she is all the time!

LW: Yeah, family can be annoying or worse. Some people need to put space between themselves and their families [like S had to do with her dad and stepmom] And I appreciate that you want to help me. I guess I should think a bit about how often I complain, but what I really need is mostly to be listened to, not [overly drastic] solutions. Thank you for listening to me and I'm glad to know you have my back if something truly awful happened.

and hug

... maybe not as firmly boundary setting as Prudence suggested, but I think it might help.