Husband caught trying to download child !??!!?

We have been married for 7 years. Have 2 kids, a boy (7) and a girl (2). He is in the army. We were together for 3 yrs before we married and since then he has always lied to and kept things from me and done things behind my back. I have done my fair share of bad things too so I decided to call it even and forgive him, basically we forgave each other and started over...Well he was deployed 06-07...when he came back in October of 2007, a few months after his homecoming I found a flash drive in one of his ACU pockets. I asked him what was on it and he immediately started getting defensive and trying to fight me to get it. I asked him, what do you have to hide?? are you cheating on me?? is there pics of another woman on here?? He denied all of that and finally admitted that there was a video on there of child . He said he got it along with a bunch of other (regular) from a buddy of his out there. I asked him why didn't you just throw it away when u saw what was on it? he said he was afraid someone would find it. so i asked him why didn't you demolish it into a billion tiny pieces? he says he was afraid the Hajis would find it and put it back together! i was like WTF?? so anyway, i decided to give him the benefit of the doubt and we both got rid of that flash drive right then and there and threw it in a dumpster...Well that was nearly 10 months ago...YESTERDAY, i found something on my computer that he had tried downlaoding off of Limewire...it said 13 yr old pregnant **** gets ****** and whatnot...i was MORTIFIED. He got defensive and confrontational and told me that HE pays for everything in this house including our internet AND our computer....I told him I will file for divorce and take away our kids from him. I want FULL custody and I also want child support. I dont want him around our kids for obvious reasons!!!!!!! What do i do???? He has been crying and pleading all day yesterday that he loves me and our kids and doesnt want to loose us....I love him with all my heart but now I also have to think about the kids becuz of I caught him doing online! I mos defenatly dont want him around my kids. We currently live away from home due to the army (we are in NY right now but we are FROM TX) Im a stay home mom with no income of my own, he supports us. So its not like I can just pack up and leave right now. Which I wish I could do....I have to wait until August when he has 2 weeks vacation and he is going to drive us home then (he deploys in october again anyway). What should I do??? Please help, my childrens lives are at stake!