Divorce/separation/house sale advice please

I'm in the early process of attempting to split with my husband after 12 years of marriage. It's myself who has initiated this, and my husband is not in agreement, as he is worried about the negative effect this would have on our children, and that they would not get as much, financially, as what they do now, due to both of us having to pay separately for bills, council tax, rent/mortgage.
Neither of us have cheated. I feel we have just grown apart. He can be very controlling, and manipulative, and I'm not in love with him as I used to be. I have felt this way for over three years, but have stayed, due to the impact separation would have on our kids, but I now don't feel I can do this anymore. I have to move on.
My original plan was to find somewhere to rent, and move out. Then to sell the house, and with whatever money we have after the sale of the house, we would both, hopefully be able to put down a deposit on our own house. However, the houses for rent in my area are expensive and, financially, at least, it would be better if we could stay under the same roof, until the house is sold. I don't know if this will be possible though.
We own our house, jointly, and have lived here for five years. The house, when we bought it, was valued at 110,000, and we managed to get it for 100,000 so 10,000 less than the asking price. We got a 95% mortgage (95,000) and we have 84,774.34 left to pay on the mortgage as of this morning. My husband states that by selling now, we would lose money. Does anyone know if this is true?
I'm also currently looking at our debts and trying to see how we could minimise these. I'm hoping we can both take out a money transfer credit card, and pay off half the debt each, and then pay our own half back over a longer period.
Advice on how to tell the kids as well? My oldest is almost 15, and my younger two will be 12 soon. I feel they are old enough to understand, and they are good kids. I feel that so long as they can see that both myself and their dad are happier, and can get along for their benefit, they will not be as scarred as they might be otherwise. Maybe that's naive of me to think though, and their dad certainly doesn't think this way. He would rather us stay together until the kids are old enough. However, although I used to feel this way too, I now believe that there will never be a good time to tell them, and as selfish as it is, I can't go on being unhappy. My son will have exams starting next year, and my younger two will be going into first year, which is a big thing too. I would rather have all the kids settled before this, to lessen any detrimental effects on any of them.