I think that you have to prioritize - no human can do the four things you've listed at max capacity for each. It's just impossible. You can have a Dad, have a part-time consultancy, be working on your startup "on the side" for 15ish hours a week, and go to school part-time. That works. But there's only so many working hours and so many play hours to go around.

168: Hours in a week

50: Hours of sleep a week (average)

========================

118 hours of work and play

60 hours a week of working

58 hours a week of playing

Of those 60 hours, it's just a matter of priorities that week in terms of what goes where. You can't work full-time on the consultancy, the startup, and be the degree - just not enough hours in the week.

The reason I spell it out like this is that sometimes our mental approach to a problem causes stress for us. If you have it in your head that, "I'm trying to do my consultancy full-time and get my degree quickly", then man - that's just a lot of pressure when you look around and go, "Holy crap - I've hardly worked on my startup at all today! Sorry, honey - I can't play with little {insert_child_name} today because I need to work!" The right frame of mind makes a lot of difference IMO.

Best of luck!