I've got two boys also (three if you count my husband ). They are older 14 & 8 and though they are probably more independent than your boys, they are a huge distraction when they are around.
I workout at 4:30am every morning to make sure that nothing gets in the way. Sounds drastic but I had to ask myself; how bad do you want it???
I wanted it BAD
As far as your cardio, I would think that low impact steady state cardio 3 days per week (the days you don't do the Pump class) would be best but check with your doctor. I would stay away from any high intensity cardio. My husband has an enlarged heart and he has to be careful also.
Also, how's your eating? You are doing a Body Pump class 3 days a week. Are you eating clean? Are you eating enough? Take a look because your nutrition is 80% of this whole body equation.