Although you may never have gotten married, the legal system could view your relationship as a common law (informal) marriage. Perhaps you have heard of this term before. Unfortunately, this is a lot of misconception about what constitutes a common law marriage. For example, many people believe you must be with the other person for a specific time period, but this is not true.
There are three elements needed in order to establish a common law marriage:
1) The man and woman must agree that they are married,
2) They must cohabitate (live together) as husband and wife, and
3) They must hold themselves out to others as husband and wife.
Without more facts, I am not sure if your relationship would qualify, but if it does, then upon a divorce, your spouse would be entitled to a "fair and equitable" distribution of the community property. This is commonly referred to as a 50/50 split between the husband and wife, but it doesn't have to be. If one party has committed adultery, then he or she could receive less than "50" percent of the community property.
Texas law presumes that anything acquired during marriage is community property (exceptions are things like a gift, inheritance, etc - which are the separate property of the receipient). If your house was bought during the marriage, then the presumption is that it is community property. However, you can overcome this presumption with a method know as "tracing." Bascially, if you can prove with financial statements that you paid for the house with your own separate funds, then you could get the house as your sole property.
I hope this helps you out. You should really talk to an attorney because you have a lot of possible issues to deal with. Even if you are not informally married, you still have a custody issue to deal with. Best of luck to you.