It is obviously harder to go through med school having a spouse and children, but it is still feasible.
Having a spouse can be a positive thing, because a lot of single students complain of feeling lonely and of being cutoff from life in general. Having a spouse can be a tremendous support, as long as both you and your spouse went into med school as a joint venture and you both knew well what you were getting into. What that means is that your spouse should not be jealous that you will be spending a lot more time with your studying buddies than with her. That you will be too pooped to even think straight sometimes or too stressed out and go ballistic over minor things. You need a strong relationship before med school and you also need to forewarn your loved one that you may not be the most pleasant person to be around for a substantial part of your education.
Kids add an extra stress, because it is hard for them to understand that "daddy is too busy right now, because he needs to study" or that daddy will come home often way after they have already gone to bed and get up before they do. Consequently, it is impossible not to feel guilty, at times, of "neglecting" your kids. I think this is particularly true for the moms in med school, more so than for the dads, because of our social expectations from each parent. Again, your spouse has to be willing to "save the day" and give your kids the extra attention they will need.
My spouse, who is looking over my shoulder (I have just been told it is not "over my shoulder" but from "a cloud above") says that as long as you have "super spouse" by your side, things will be fine. That is, someone that takes care of the bills, takes care of the kids, takes care of the daily routine at home, and so on...LOL
It can be done! Many people in my class, including myself, are doing it right now! Talk it over carefully with your spouse and good luck!