I'm going to leave the country without telling my mother whom I have not spoken with for more than 10 years
Why do you want to leave the country without telling your mother?
Because she always brings negativity into our conversation. I want to get away from her.
You should not just cut off your mom. That's really rude. You should let her know what is going on. She may need to contact you in an emergency.
If I do tell her, she will try to stop me. You should realize that complaining won't change anything. Your life is your responsibility.
It is normal to talk to your parents and tell them about you major life changes. It might be worth trying to repair your relationship with her and have a healthy one going into the future.