Paid the deposit but no longer qualify for mortgage, how to get out of deal?

OP - the most important thing you do is check if you can afford the mortgage repayments before you try and go ahead with the purchase. No point getting parents into trouble as well. If you can't afford it then really you shouldn't buy it. How much will the bank lend you on one income? You could maybe renegotiate the price with the builder down to this level. How much are apartments currently selling for in this estate would be a good place to start in your negotiations? You really need to do the maths.

How old are your parents? Are they close to retirement? Will they need the money that you won't be able to afford to pay them back? How will they pay for nursing home care otherwise? Will they be able to afford any payments you put them up to? Will you cause a family row with any siblings you have?

IMO, you should leave your parents out of it. If the developer does nail you to the wall, to complete and you have to declare bankruptcy to avoid it, you will need their help then. Getting yourself into a situation you can't afford with stop-gap measures is just asking for trouble later.

Hi,just off the phone from the mortgage brocker. they've told me that if we have signed the letter of offer (which we did) bank will not be looking for any more paperwork to complete now. the risk is still there coz we are taking 97% mrtg but at least some ray of hope! They also tald us to keep the parents out of it but only because it would mean to re-apply/ new application. and that = to forget about 97% and get 85% at most!
thank you again and i'll let you know how we get on.
Ro_Ki