I have namechanged as H knows my other one but wouldn't want him to find this. Hope I don't out myself!
H was SAHP to our 2 DC but left at New Year as he didn't know who i was anymore, had been miserable for months and loved me but wasn't in love with me. Out of the blue and he is now with someone else who i strongly suspect he was cheating on me with 
He no longer looks after the children full time but does have both one full day a week and DS (1) for two other days. This is in addition to one overnight a week and every other weekend. So, in short - more than a lot of NRP's i guess.
He is still unemployed but looking for work and claiming JSA. I just wonder if legally he is entitled to some sort of financial support from me. I get all the tax credits and child benefit but am obviously now using childcare where i didn't before which is expensive. I also provide him with everything he needs for them for the days ie lunch, nappies, spare clothes and pay for anything they need day to day ie shoes, haircuts, new underwear - well, you get the picture.
I just don't know if I'm being fair. I was giving him money when he was continuing to have the kids more but i just can't afford it now. I often think if the roles were reversed, he would be expected to pay me. I then think - he chose to leave giving me no warning, he immediately 'found' a new girlfriend & is living rent & bill free whilst i struggle on... But am I being spiteful because he hurt me so badly & I should help him..?
I know i should get proper legal advice and will do at some point but some advice would be welcome!