Too much of it, at least.
What other seemingly harmless entities might be harmful to your well-being?
If you find that certain people in your life bring nothing but negativity, hostility and strife, take immediate measures to eliminate contact with them. If you are serious about completing a project or maintaining a happy and healthy existence, hanging around friends or family that that lower your quality of life is not advised. The world is a tough enough place; You don’t need any additional forces undermining your efforts. You can still maintain a civil relationship with this person. There is no reason you cannot call or meet with him/her on occasion.
I want to stress an important point; there is a difference between helpful constructive criticism provided by well-wishers and insults motivated by ill-will. If family or friends are providing practical reasons why you should not (or cannot) pursue a particular course of action, consider listening to them. There is much to learn from vantage points outside of your own. Do not avoid someone solely because they are telling you something that clashes with what you want to hear. You are doing yourself a great disservice.
Before you cut someone out of your life, you should talk with with him/her. Voicing your displeasure directly to this individual may mend the relationship. It is entirely possible that the person isn’t even aware that you are unhappy. Calmly expressing your thoughts and feelings (AND listening to what he/she has to say) may resolve the problem.
If you still find that frank discussion yields no change, just move forward without that person in your life.