Gonna try to sound all wise and grown up now..
The thing is even when everything is running smoothly no one can be the perfect worker, partner,parent and look after themselves. Balls fall. So it's unrealistic and by the sounds of it quite harmful to yourself to try and do it now when even more people want a bit of yourself and they all intermingle.
So start prioritising... time for yourself in the morning (you're up at the crack of dawn anyways) .
Then work is work, your kids are older so can entertain themselves and look after themselves and they have your partner as an extra adult. If at all possible don't do everything at work just because you can or think you should. Work your hours if possible, take your breaks and lunch and then when you're done you're done.
Spend some time with the kids,have dinner ,watch a movie etc.
Another walk or whatever for an hour to yourself.
Hang out with you partner .
Work won't build you a statue at the end of this, hell they probably wouldn't give you the clap. 
Your partner is a grownup and must understand that you need a break, from everything including him and he should be supporting that.
And your kids won't end up in long term therapy because mum needed to be shits and not mum once or twice a day.
Sometimes good enough just has to do. Hell good enough is going above and beyond really.