Breaking Mother/Adult Children Boundaries

I love my mom, and we are somewhat close, but she has been stepping over boundaries a lot more lately with my brother, me, and our kids. We had a heart-to-heart talk with her 7 years ago about her breaking boundaries and her negative actions; it didn’t go well. She wouldn’t speak to any of us for 6 months or so afterward and gave us the silent treatment.

We are treated like children. We are 38, 36, and 34. She is intimidated by my middle brother because he’s a lot like our dad (successful, has his own company, can buy anything he wants(?) – With her, it’s always been all about the money, and how we couldn’t afford anything).

How do we talk boundaries with our mother without her feel as if we’re attacking or hating her? She calls me a lot to vent, even though I’ve told her many times that she’s crossing a line, but is not respecting it. What is going on with this situation? I am so lost when it comes to coaching myself through my OWN stuff.

Thank you, Coaches!