How do you know it's time to end a friendship?

My friend is the kind of person who is introverted , tends to be too pessimistic at times and always argues with you just to have the last word. Despite her flaws, she has a good side and was there for me when I needed her. I liked the fact that she was never fake to me. The problem is that as the years went by, she became a bitter person who almost seemed like she resents happy people. She's incapable of having a relationship because of her abrasive personality. I feel very fortunate because I met the love of my life and I am thankful for everything I have. She's always criticizing my projects and aspirations as if she she doesn't want me to keep on being happy. Whenever I am happy, she acts like a Debbie Downer. I confronted her about it and she told me I was paranoid. Is it time to end this friendship?