I live in a non-Muslim country, My husband has small business, and he has debts to the bank.I’m working, and I hardly manage hardly the expenses of the family.We are building a house now with my parents help1.Must I pay zakat ? Is it better to pay zakat monthly or yearly?2.Must I pay zakat on money that I saved a few years for something (like education for my daughters) ?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Zakah is not due on anything that is for personal use like one's car, house, etc. But it is due on any income that reaches the Nisaab (the least amount that makes Zakah obligatory on utilities) and if a lunar year passes after possessing it, if it is not an agricultural product as the Zakah of agricultural products is due as soon as they are harvested.
Now if the person is indebted and has something for which he has to pay Zakah, he should do the following:
First, calculate the debts.
Second, deduct the amount of these debts from his belongings that are subject to Zakah provided his extra valuable personal things such as houses, cars etc. cannot pay his debts.
Finally, give the Zakah of what remains after debts were paid.
Zakah is not obligatory on a monthly basis; it is yearly and is paid roughly on the mentioned properties that reach the Nisab.
Now if you amass some money, and this money reaches the Nisaab by itself or gathered with other properties (goods…) and if a year passes after you owned it (regardless of the purpose for which the money was amassed; building a house, marrying one's son…), then you have to give its Zakah.
Allah knows best.