finances destroying my relationship part 2!

not sure if anyone remembers my previous post.
my partner and i took your advice and went to see a solicitor yesterday (not free advice £285/hr!)
the solicitors main interest was what his house is worth and the complications of inheritance/trustee issues and ISA values.
my main purpose was i was expecting to be told he was paying too much maintenance and setting himself up for possible spousal maintenance.
kids are 20 and 18. 20 has finished 2nd yr in uni and 18 is due to go this time.
he has been paying £750 for last 2 years.
solicitor said he has to continue paying until both have finished uni.
he seemed to be saying he is responsible until they have finished and worked out he should pay approx £400/month to the ex.
he arrived at this figure after briefly looking at her cost of living so it felt more like he is supporting the ex and not the children who will be at uni for 33 wks a year.
will this be even if they get a divorce.
she earns £20000 and we earn £230000 each
whilst i completely agree that kids dont become free to run when they turn 18 and i would expect him to provide some ongoing support for them i thought it was only an expectation until they finish a levels.
if this is the case should ui be getting support from my ex for my 18 yr old who is also due to go to uni in september.
is the reason he is being asked to contribute becasue she hasnt moved a new partner in?

Is there a signed Consent Order in place stating he has to pay SM?
CM finishes when the child leaves full time education -A levels or equivalent. I only know this as I tried to get some maintenance off my ex to help with my child''s Uni expenses etc.. And was told he didn''t have to give anything as the law states that at 18 our child was an adult?! if maintenance was needed an application would have to be made through the courts by the child direct? If there isn''t a consent order and help is needed for uni costs could your partner give it direct to the child?
Why did the solicitor say he had to keep paying ?

i have no idea - im now feeling my partner had a pre meeting with the solicitor to suggest he said that as he wants to continue to support and i feel the support is a little high.
he didnt ask if they were going to be living in at uni or anything to do with them - it was all about her living costs and their wages.
there is no consent order yet but he has been advised this needs to be negotiated.
could it be he just pays until there is a divorce to keep her happy until then.

i also have an 18 yr old and have had no support for a yr.
she goes to uni in sept without grants becasue on paper our earnings are £46K but in reality he gives almost half his wage to the ex.
his kids both get full grants because their mum is a single parent

If there is no consent then there is NOTHING saying he has to support his kids until they finish uni. As previously stated by Chocoholic- his legal duty ends at 18 or full time education (which does not include uni- unless privately agreed).

then all i can think is it is to keep things sweet until a consent order is granted

He shouldnt overpay- as that is will be seen as the status quo and the courts will view this as sustainable. He needs to be very careful of that.