Hi, this is a very difficult thing for a wife and mother to go through. I understand. I am in a situation with a few similarities. My husband is a member but not active and becoming more and more disillusioned with religion. (that is kind of beside the point. I just wanted you to know that I understand a little but my shoes are a little different than yours.)
First of all, you will not be able to become the only woman he will look at. You can dye your hair; wear sleazy clothes and augment whatever you want but he will not stop looking at other women. Hang on to your standards for yourself. You are a daughter of God and don't demean that for your husbands sake. My husband had a nude woman painted on his motorcycle. I told him it was pornographic and he told me it was art. There are all kinds of excuses for a man to view other women. "I appreciate the human body." etc...
As for seeing the bishop, he may not be able to give you the advice that will turn your husband away from looking at other women. Your husband is the only one who can do that. It is an addiction and he will have to want to stop. But the bishop or any other worthy priesthood holder can give you a blessing to give you strength or comfort. Arrange a time during Relief Society or another time when your husband is busy. The blessing is for you and it is personal.
Also people talk of leaving your husband, I don't think anybody understands the logistics of a single divorced mom with 8 kids. Even with child support it is something that would be very difficult even under the best of circumstances.
Watch over your children. Protect them from your husbands actions. I don't know how many sons or daughters you have but you don't want your sons to view women as objects and you don't want your daughters to feel as if they are on this planet to be gawked at. Keep praying. You have a lot deal with.
Enough said on my part. Hang in there. Realize that you are not the cause or the cure but do what you can to protect yourself and your children.