I'm grappling with the future

I have been separated for almost 6 months, after 20 years of marriage moving out of the marital home in March. I am paying £600 per month (23% of my net income) to me ex as child maintenance and meeting 50% of the mortgage on the marital home. My ex didn’t work for 10 or so years of my marriage, receiving sickness benefits for the majority of that time. She retrained as a teacher with my financial support and now earns about 20% less that I do, so after child maintenance has more ‘income’ than me. I have agreed to continue paying child maintenance directly to my kids after the age of 18 until the both finish full time education. My question is, am I likely to have to pay spousal maintenance?

The overall circumstances are relevant and it's impossible to say without the detail - respective incomes, liabilities, ages, any disabilities, and the number of children, their ages and how man nights they are to spend with each parent.

Generally speaking people on average or below average incomes do not usually pay SM and it isn't paid when there isn't much discrepancy n incomes. Also it depends on the split of assets - the less capital there is to house someone the bigger mortgage they need, the more likely they might be to claim SM particularly if their housing needs are greater because children live with them the majority of the time

At the moment there is no capital - in fact together we have £60k of negative equity and £25k of unsecured debt. I have offered to continue contibuting 50% of the the mortgage (400/mth) to allow her and the kids to stay there until my youngest (now 15) enters full time education but, have agreed to take 60% of the debt should she want to move now. If she does stay my offer is to give her 55-60% of any equity that might build up. I earn £42k and my net earnings are £2600 per month and she earns £31k and with benefits etc her income per month is £2225 before adding in my £600 a month child maintenance. I can just about make ends meet in rented accomodation at the moment so any assessment of what may happen in the future re SM would be appreciated.