Possible Duplicate: How to start a business and not destroy your marriage?
Not everyone starts their business when they're in/fresh out of college. How do you deal with your spouses and help make them understand why you do what you do?
Better question, what do you do when one of your partner's wife's... doesn't seem to be playing with the same playbook as the rest of the extended family?
Be open, be honest. Sit them down and tell them how important this is to you. Make it clear that it is not a phase you going through, but something that you really need to do. You'll be surprised at how supportive they are when you tell them something you are passionate about. It's also a good idea to keep them informed. Tell them when something goes wrong, tell them when you've made a breakthrough.
Some wives/husbands won't accept this, and if not then there is some deeper problem that needs resolving before you move forward.
There's been a couple of great threads on here about this already. Have a look at:
How to start a business and not destroy your marriage? The other question I would be asking myself is "What needs does she have that are not being filled? and How can we (and especially her partner) help fill them?" If she has her needs meet, she is far less likely to be obstructive about the startup.