How to tell him it's over?

I've been with my partner for 6 years we live together and have made a home with each other.. But sadly things have come to a stand still for the past year I have been struggling with this relationship he's been in and out of work and up and down with his emotions and I found I have grown  sick of it.. I have arranged to go and stay with my friend for a while so I can save some money this is happening in three days time and he still doesn't know I'm leaving.. The reason I haven't told him yet because I know he's going to kick off. I have started packing up things that I know he won't notice that have gone I only have a few more bits to pack my current plan is to get back from work on Saturday morning grab my things quickly put them in the back of the car and go and not tell him where I'm going because I know he'll be banging on the door.. But obviously once I stop putting things in the car he's going to know my question is how do I tell him its over without him kicking off and destroying my things? I know his mum and dad will be around kicking off as well.. This can be one very messy situation that I need to get out and I need to start my life again... Help me!!! What do I say!!