Marriage advice

My husband and I have been married for 19 years and I am starting to notice that he assumes everything i say before I say it and some of it isn't remotely close to what I was going to say. If I try to explain myself he blows me off and talks about something else. This is starting to make me think that it is time to leave. We have 3 children, 1 in college and 2 in High school. I would hate to that to them, but i'm not sure if its the best course of action. If anyone knows how to communicate with a person who won't shut up long enough for you to say what you need to would be awsome.

need some more info : it seems to me 19 years of marriage can not be swept just like that under the carpet for communication reasons - there must be more to the story :)