OP. Try wikivorce as well.
But hope this helps:
My ex did the same. Moved into OW house. He wanted to sell the matrimonial home and give me the capital, pay 15% maintenance until our DD reached 18 (she was 16 at the time). in exchange he wanted to keep all his pension. He moved to a cheaper area too and I stayed in our home town which is expensive to buy. I had worked but earned less due to having had our child.
This deal didn't sound good for me as I too thought I could only get a 16 year mortgage due to my age. I went to a sol, we tried mediation, failed because I went in with a different set of expectations and ex realised that neither the mediator nor me believed it to be a great deal.
So:
Tnrough negotiating via my ex (who didn't consult a sol through choice until the draft consent order) and my sol we agreed:
I took most of the equity to enable me to rehouse me and DD. I got 38.8% of his pension which amounted to a 50/50 split of the entire pension pot. 15% maintenance until DD is 21. Spousal maintenance for 5 years. He also pays her boarding fees at a 6th form college and I pay her food costs.
I have just secured a 21 year mortgage with the agreement to pay 10% overpayment per year which I can do.
See a good sol OP. Try not to panic, they'll work it all out based on the length of your relationship, your joint incomes, assets, liabilities, age of DC's, etc. Your sol will advise and negotiate on your behalf, that's what they get paid for.
It's scary, but entirely do-able. 
HTH