What should i do?

ok here goes...My fiance and I were planning on getting married in 9 months( no im not preg.)We have been together for over 3 years and living together for alittle over a yr.; and at first my parents were going to pay for it. Unfortunatley my mother and i have a very bumpy relationship, we are not nor have ever been close. For the past few weeks she has been bi-polar almost, about the whole wedding. one she'll pay for it the next she doesnt want part of it then she does. So knowing my mother very well( i knew it would turn out "ok") I cancelled the wedding. she just got all the deposits back today. Last night my fiances father offered for us to move in with them so that we can pay for our own wedding. His family is VERY tight on money and cant help out financialy. Both my fiance and i work and of course will be giving money to his parents to help out with electricity, food...my relationship with his family sky-rocketed when we announced we were getting married..what should ido????