I know exactly what you are talking about! I finally told my youngest, "If you aren't going to make any changes in your life, I don't want to hear about your woes all the time." As a mother, it is very hard to hear my offspring crying about how awful her life is, yet repeating history over and over. That really grieves me, and tires me, and I decided I'm not obligated to keep listening. The silence has been really nice.
I had to learn that offering a perpetual sounding board for a miserable person, including family members, just enabled a pattern of destructive behavior in both of us. The word "no" is so super powerful, and yes, I truly cherish the silence. I just remind myself that I am there if that person is ready to move forward, but I am no longer available to roll around in the pig pen of misery with them. Tis a hard thing though, I am sorry you have had to go through that.