Does my spouse always get half of the house even if I paid for it?
If you are married without a marriage contract then the answer is usually yes. There is a specific law in Ontario that the presumption is that each spouse will always receive 50% of the equity in the matrimonial home. In a common-law relationship where the rules for property division are more along the lines of whoever owns it keeps it this is not the case.
If you do own a property before marriage which you believe will become the matrimonial home you should consider how to protect yourself from this result.
You can protect yourself from this result by having a lawyer draft a marriage contract for you and your wife to sign. Both parties must receive legal advice for such an agreement to be binding but assuming that you have followed your lawyer’s recommendations this type of agreement should be able to protect for property from division.