Is it vital that you work 45 to 50 hours a week? If so, you will probably have to do some comming to terms with the fact that a huge chunk of your waking hours every week are already gone.
Assuming that your work schedule is immutable, you should probably figure out what your needs are and what will work best for you. One contiguous block of 4 to 5 hours every week or some preset half hour block every day... and once you've figured out what might benefit you best, communicate to your loved ones what your needs are.
Example: "Every Friday night I need three hours away from EVERYBODY if you all have any hope of me being a sane person for the weekend. How can we make that happen?"
Any of our suggestions sound like they're heading in the right direction or do we need more information on your situation?