Right here should tell you that you didn't mean anything to him while you read too much into his using you.
The grass isn't always greener and love is a commitment it isn't about feeling the sparks.
Try to find what it was about him that you once loved. Find it in yourself to have a change of heart for your husband. If it takes going to marriage counselling do it.
Also if you do divorce your husband can not simply say the kids stay with him. You go to family court and file for primary custody and child support.