Out of Control

My life feels like it is spinning completely out of control. My sister has joined the army. She is going to leave 3 kids behind while she goes to basic training. I don't have a problem with someone wanting to join the military. I have a problem with someone wanting to join the military when they have 3 kids. I can't understand how a mother can leave her son's 12 & 7 and a beautiful little girl who will be 6 behind. She had her oldest at 15 years old. She is all he has ever had and she is going to run off and leave him with his stepfather. For the past few years she has been a full time mother how can you just leave like that? I just don't understand it. I hope those kids know I will be here for them. I love them to death and will do anything for them. I am losing a lot of respect for my sister. What would she have though if our mother had done the same thing to us?