husbands ex and a mortage

[debsybabe]

my husband split up from his ex 3 and a half years ago, he still pays mortage on house they bought together, she has never paid anything into to the mortage and now we are expecting a child together and hes extremely stressed about being able to afford things, i work at moment and pay rent on the property that we live in, i've told him to talk to ex but seems like i'm banging head against brick wall, what options do we have , they have 8 year old child together