I'm not going to speak to my mother for the next 10 years.
Ten years? Why would you avoid talking to her for such a long time?
It's because she is trying to stop me from being with my SO
I understand why you'd want to cut her off then. Nothing says we need to maintain relationships with a parent if we don't want to, especially if they're upsetting you. 10 years might be a bit excessive though?
It's not excessive with how much pain she is causing me by imposing her worthless advice.
You don't need to have a relationship with anyone, even a parent, if you don't want to, but maybe you should think about her advice. She probably doesn't want to hurt you, and there might be some wisdom to it. Conversely, you might be able to see where she's coming from and correct her about your SO.