I don't want my wife to leave me alone with her kids for 2 to 4 nights each week.
Is there a reason you don't want to care for the children?
I'm tired and I feel like I'm the only one that's doing the work.
Taking care of kids can be exhausting, and it's easy to grow resentful of a spouse that you feel isn't pulling their weight. However, as a parent it is your responsibility to help take care of your kids you can't expect your wife to always be there to assist you. Try to be more understanding, especially if your wife is having to work.
Her job is less important than my job.
That does not matter, if she is not home you need to care for you kids. If you can afford it you could always discuss getting a nanny to help out.