The way i look at it, you need a short term and a long term plan.
Short Term, is what you do come monday morning.
For this, i'd go back and patch it up with him. Explain what is frustrating you and try and get the sympathy vote. You only get one dad, so you don't want to burn bridges and leave on hostile terms. You'll regret it if you do.
For the Long Term, i'd look at getting money put away to facilitate the setting up of your own company to give yourself some options. You can leave your dad if things don't improve further down the line.
Plan B of course is try to turn the company around so this doesnt happen. Hire a new guy to help you with installations and stuff that you can train up. Get a 3rd person involved so that takes the weight off you. This should then give you the time to make improvements elsewhere in the business. Get a proper record keeping service going. Get new computers so you can keep proper track of stuff and take it away from pen and paper etc..
I've got a best mate who did exactly that with his dad's business. Only you know if your dad will let you do it and not resist the modernisation however.