You can definitely do it! My motto, which I've lifted from FitFabJen, who also had to lose the same amount as we did, is "progress, not perfection." No matter how many times I make a bad choice, I try to get right back at it at the next opportunity. Over time, that really makes a huge difference.
It's harder, I think, when you have small children, mostly because of the time factor for exercise. But as you know, sometimes to do the best for the kids, you have to have a bit of time to put yourself first. : )