More likely than not, the house will be considered a marital asset and you will have been considered to have gifted her half of the value of the house when you added her to the deed, unless you have something from her in writing stating otherwise. You should consult with an attorney in your area before making any decisions.
Please note that THESE COMMENTS ARE NOT INTENDED AS LEGAL ADVICE and are for informational purposes only. This response is not intended to create any attorney-client relationship and is only based on the limited facts given. The response might change should additional facts be learned and should not be relied on as legal advice. It is recommended that you consult with an attorney who can properly assess the situation, as well as all pertinent facts, prior to taking any action based on the foregoing statements.
Ms. Mitchell is right. Under Florida divorce law (I assume you are contemplating a divorce), a house which belongs to a person before marriage does not become marital property. It's "premarital property." but Florida law says that when you add your spouse to the deed, the house becomes marital property.
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Perhaps you can keep the house. The outcome of any divorce case depends upon a number of factors. You need an attorney to help you negotiate a favorable solution if and when you file for divorce. If you owned it prior to marriage and put her on the deed for survivorship purposes, there may be caselaw that helps you. Consult an attorney.