You probably should tell this person that you have clearly made a mistake mixing your husband's business with your personal life, because she is doing nothing but pestering you. Tell her she is wasting her time because she is annoying you so much that you can't even refer others to her; you cannot suggest her as a realtor when she is relentless. She is hurting her own business because she is spending all her time talking to people who aren't in the market. She's wasting her time and missing out on potential sales because of this. She's spending too much time talking and not enough time listening. She is not hearing you that you aren't in the market, and she is not hearing you that the houses she is choosing are too expensive even if you WERE in the market, which you are not. Say it as a "word to the wise" to be helpful. If she is contacting you, she is contacting other people with "Want a house? No? Okay, how about some makeup?" She's going to get a bad reputation in the community and be avoided like the plague. But be insistent that she should not contact you again - you will contact her. It's not up to you to protect your husband from being awkward - as you say, he's the one who crossed the line. And I'm not sure that she didn't engineer that by talking to him about how she had not money for prescriptions. Does she think all doctors are wealthy beyond belief? Your husband can do without this patient if that's what it comes down to. OR, he can be the one to tell her to stop calling his home.
FYI any good direct sales company (like Mary Kay and many others) will tell its distributors to STOP being annoying - that it's not effective in developing a network, that it damages the company's reputation, and that it just sets the distributor up to fail. They have to broaden their networks, not keep harping on the same people. Real estate agents at good realties are trained to send out occasional helpful notes about tax rates or mortgage rates, just to stay in someone's mind but NOT to harass them! So she's completely going against what the successful realtors and Mary Kay salespeople do. She is doomed to fail.
I think it's okay to reach out to friends and relatives when you have a business. If I opened a store or became a car dealer, I'd let everyone know. You never know who is in the market, or who they know. Businesses work on referrals from satisfied customers. If I have to buy insurance, I'd just as soon give that business to a friend or relative assuming rates and service were equal. I mean, why not?
Where these people are going wrong is when they don't listen to "no" and keep harassing you. So the first invitation is fine and shouldn't annoy you. If it's not for you, you can always refer someone else you think of. If you don't want body wrapping now but might like to in the future, you can let your cousin know that this time doesn't work out but to invite you again. If you DON'T want to even consider body wrapping, then don't be so inviting. But that's on the first contact. After 2, the cousin should move on.