I commute to med school, had twins, and my wife and I own a pharmacy so take this with a grain of salt. My wife gave birth to our twins a week before our head and neck exam in gross. This was Sept 30, 2003. We survived, but there were moments where we both wanted out. If we didn't have the little guys we would have split up. My wife and I love each other very much and the experience of parenthood/med school/owning a business has made our bond stronger, but sheer force of will, antidepressants and love for our children is the only way we made it. Unless you have a superb support system you will NEVER have a moment of peace or time for yourself for the first two years at least. My guys are 3 and still demand a great deal of attention. One of my favorite questions on the interview trail this year was when they asked about hobbies. My answers were all in the past tense because now I have none.
Now with all that being said, I am graduating in May at the top of my class, AOA, good boards, blah, blah, blah... so it can be done. It is just a matter of how much of you will be left when you make it out the other end.