Waving my white flag...

I don't think I have ever been more overwhelmed than I am right now. I am a mother of 3 with a husband who works out of town. He has been gone for 3 weeks already and is expecting to be gone for another 2 weeks. I feel very alone and like I am at my breaking point. My youngest is almost 5 months old and still has colic which makes most nights unbearable. I find myself crying right along with her because I just don't know what else to do for her. I put on the happy face day in and day out because I don't want my children to pick up on how mommy really feels. I am responsible for all the household things which isn't a big deal but when you add a very cranky baby to the mix I feel like i'm failing at being a wife and mother. I should be able to do this right? Dishes, laundry and dinner should be an easy task for most right? Well not for this mama. I don't know what to do anymore.