I'm going to ask my boyfriend to leave me.
That's quite serious. What happened when you asked him to let you go?
When I said it he kept badmouthing what I'm saying without considering the feelings behind it
If asking your boyfriend to leave you is not a serious request then you should rethink saying things like this that you are not sincere about. Your bf may feel manipulated if you make requests that seem like they have another motive behind them. Try addressing the underlying issues that your bf is not looking at and work things out with him instead.
Oh, I might not have expressed myself clearly so let me try again.
That's all right, a lot of things can easily overwhelm us! I believe it's best to think hard before you say something, to make sure the best move would be made! Good luck with your relationship.