My husband is leaving....

He has got a new job and it will be a lot more money.  Instead of making between $1000-1500 a month it will be closer to $3500-4000 a month.  The problem is that it is in Montana and we live in Texas.  He will be working on pipelines that are coming south.  He will be gone upwards of 4-6 months at a time.  He will be getting good insurance and everything.  I know that we need this.  This will help us catch up on all of our bills.  But, we have 4 children and I am so worried that the twins are going to forget their daddy because they are only 7 months old.  I'm gonna miss him so much and I am so depressed but at the same time I am happy for this opportunity.  I'm so confused.