How to handle this break-up !!!?

Hi people, I have tried ending my relationship with my girlfriend because u feel as though we are taking each other for granted and despite having spoken about it over and over, it's not getting any better. I have suggested that we part ways and pursue othe relationships but she won't agree it. We hardly communicate and when we do, we jus fight. I know it ain't easy to break up after 3.5 years but it's becoming clear that we have to do it. I have spoken about it with her but she says no even though she's doing nothing to change the status quo. How do I drive the point home and end it ? Do I Ignore her calls ? Not call her ? Or WHAT DO I DO ???