Struggling

I'm struggling tonight.  After getting all the kids in bed I just started crying.  I don't know how to do this.  Three kids is a lot of work and without Dave it seems impossible.  My family is so supportive but I hate relying on them for everything.  I can't seem to get anything done.  My house is a disaster.  I've just about fallen off my diet.  I feel like I don't know how to parent successfully and that I completely suck at it.

I feel so torn in so many directions.  How much more of this can I take?  How do people do this?  There are plenty of moms with dads on the road or dads in the military.  Why can't I do this?  I just feel like such a failure.  I don't want to fail my kids.  Or my marriage for that matter. 

I want to be a super mom and a super wife.  Why can't life just be easy?