Oh thank goodness I'm not the only one who feels disgruntled towards my husband! I would tell your girls that you are very sorry when you are very cross and it isn't their fault. That pregnancy can make Mommies a little nutty and sometimes it means you'll cry for no reason, demand things be super clean, or get angry with people over things for little or no reason.
As far as the hubby food thing, leave a note with detailed instructions which will prolly be ignored since he'll want to make whatever he feels like making (or not making). For the tardy problem tell him an earlier time than the actual appointment time. I avoid telling my mom the actual time of my appointments and always put the time about a half hour sooner. So when she is 15 minutes late she still has the cushion of 15 for traffic problems and I'm not upset that she is late.
When I notice I'm getting more frustrated I will just send my son to his room. I tell him that I'm feeling very angry and need to take a short break. It saves him from feeling hurt and gives me time to get my emotions under control. On rare occasions it means he has to play in his room for most of the day. One thing to keep in mind when you are taking this break, let them do whatever in their room as long as it doesn't cause them danger or harm. Messes can be picked up, and they can learn to be more careful with their things if they break something. Repairing your relationship because you snapped at them over trivial things is much harder.