The starting point is that everything (equity, pensions, savings, assets, anything at all) goes into the pot and is shared 50:50. It is then adjusted to ensure that the children's lives can continue as normally as possible, given the thoroughly abnormal situation they are in.
If you have shared the childcare 50:50, the legal expectation is that you would share the assets 50:50, and that the children would share an equal amount of time between you. Your husband's alcoholism and infidelity are, unfortunately, irrelevant in the eyes of the law.
It isn't a question of what you or anyone else thinks is 'fair'. The law is quite strict about this, and it can be quite horrible for parents to digest. Your age is not relevant and, in fact, your situation isn't 'rare' at all. You being a woman/mother makes no difference to any settlement. The length of your relationship is potentially relevant (including any years together before you married). The fact that you are married is hugely relevant. As is the fact that you have children.
It makes no difference that you have been the main earner. You're just in the position in which men have traditionally been. My experience suggests that you will have to sell the family home and split the equity so you can both buy smaller houses. In your situation, 50:50 equity and childcare would sound reasonable on balance.