Can I stay in the house until my daughter turns 18 years old?

You need to get an attorney.  If you cannot afford one, start making an application to the local legal aid, bar association clinics, or any other program that offers free legal assistance in your community.  Court clerks and local churches usually keep a list of resources.
The house may or may not be his separate property.  I have had several clients come in, say 'it's his house, I know I'm out of luck.' However, after doing a basic title search, we learn that the house was actually deeded or gifted to the husband and the wife as a married couple... which would make the house one-half yours and one-half his.  So... visit with an attorney, have them do a title search, and double check this component.  You can also go to the county clerk's office and have them assist you with a title search on the property.
If the title is deeded to both you, it will be easier for you to be granted exclusive use of the house... at least until the kids turn 18... which would be some valuable breathing time for you.
If the title is not deeded to both of you-- only to him--- then it's a bit more challenging... but not impossibe.  When it comes to family law, everything really is open for negotiation.  It's a given that he will be ordered to pay child support, but I have negotiated in similar situations wherein the wife gets to use a house for a certain period of time in exchange for no child support from dad as long as mom is occupying the house.  So.... win, win--- he doesn't rack up a child support bill that he will never be able to pay and could get thrown in jail for failing to pay... or he can help you out with housing.
Even if he refuses this option, his house can help you down the road.  When a parent owns a home outright, then the Texas AG can place lien on the property for unpaid child support. So.. in the event that you are awarded child support and he fails to pay, you still have a remedy to insure collection.
As for property... if you do decide to leave, take first what is important.  I have had several client's leave a marital residence, leave behind a sentimental something, only to comes back to find it destroyed or lost.  If you cannot replace it, take it with you.
As for the division of property... the courts in Texas use a 'fair and equitable' standard.  This doesn't mean just 50/50 of property... if means a property division package which is fair.  If you are taking $5000.00 in extra debt, the court can award you an extra $5000.00 in property to help secure the debt.  Basically, you could ask for a higher property division because of the debt factor.
I can't emphasize enough that you need to get an attorney.  This feels impossible, but it's not an impossible situation.  A good attorney can help you work through this process and get you a better deal. Many family law attorneys also keep a list of resources handy that they refer their clients to to help with the transition outside of legal services... like help with rent, help with groceries, help with the light bill.... ect. 
You need an attorney for a couple of different reasons.  First, these are legal issues which are not easily handled on your own.  Second, you don't want to accidentally waive your interest in any share of property that you could really use for your children.  Third... you have a bad situation with him using drugs in front of your children.  If CPS finds out, they could require you to participate in services (which are never fun), because you have allowed his conduct to go unchecked.  Some CPS workers will help you... but many CPS workers have over inflated egos that are extremely judgmental of people going through tough financial times.  A good attorney can help you avoid any bad run ins with CPS.
On a slightly different note, remember that four walls don't make the home.  The heart and love you obviously give your children is what makes a real home.  You could use his house, but you don't need it because your heart is already in the right place.  You just need help working through the process.  It's out there... use all the resources... and the rest will work itself out.