Boy do you and I have a lot in common. I'm 42, married with 3 DD's, mine are a little younger than yours, 9, 8 and 5, but daughters of any age are still female eh? I too have long put the needs of everyone else before mine, changing that has probably been as hard as resisting the screaming of the cookie dough in the refrigerator. But my mom who is an ER nurse said something to me that was very profound and helpful. She said that when you meet a healthy mom, you meet a healthy family and conversely when you meet an unhealthy mom, you meet an unhealthy family. Although I'm sure there are exceptions to that observation, it is true 95-99% of the time, because somehow or another a mom is in charge of the overall health and well-being of a family. So I think you are on the right track and have identified your children as at least one source of motivation. Maybe you can find a physical activity to do as a family, walking, dancing, running, biking, skiing, etc etc. I know that when the kids are non-stop bugging me to do something I'm more likely to schedule it. I think this fall the girls and I are going to take a martial arts class together, fitness + self defense, win-win.
For the rest of it, just take it one day at a time with baby steps, and be prepared to face some bumps along the way. When I decided to begin this journey I decided that since DH and I both have weight issues, as do our extended families, what was good for me is good for the whole family. Which in turn means that I do not make separate meals for dieters vs. non-dieters, we all eat the same meals (although admittedly often I leave some of the extra carbs off my plate). My kids are doing fine with that although every so often they still lament the "no junk food in the house" policy I've established. I always answer the same way, "one of these days you'll thank me, although clearly it's not going to be today". I get a bit of eye rolling, and some pouting when I absolutely refuse to buy them junk out of the vending machine or lap the drive-thru for french fries because they smell good, but they are coming around, albeit slowly. Very very occasionally they do get some junky food, like cake and ice cream for birthday parties, I might even buy chips and make a pizza party out of it, but it's for rare occasions only, not for every day.
One funny story that's come out of this is that the day after DH's birthday it was like 99 degrees here with outrageous humidity. DH was out of town for business and we had 1/2 of his German chocolate birthday cake left, which of course was covered with homemade coconut/caramel/pecan icing. by dinner time it was just too hot to cook, so I said "let's just have cake and ice cream for dinner". My kids were shocked, absolutely speechless, but they agreed. What is really funny is that they still talk about the day mom lost her mind for a moment and let them have pure sugar for dinner. What they don't remember is that the ice cream was frozen yogurt and had about 90 calories/serving, and that the cake was the "lite" version of the recipe.
Starting weight: 244.6 lbs. 10/01/09
Pounds lost: 80.6 lbs
Current weight: 164 lbs
Goal weight: 120 lbs
Weight to go: 44 lbs
Goal Date: 1/1/13