You need to hire a lawyer, now. Your deadline isn't what you have to worry about, because if your judge grants the summary judgment, it ends your case, and if you're at the brink of losing your case and it's important to you, you'll get a Legal Aid lawyer if you're eligible, or hire a lawyer if you're not.
Linked below is a 6 year old article which may help you. It says that a response is due 7 days before the hearing. Also linked below are the Texas State Rules of Civil Procedure, which you should already be familiar with.
Disclaimer: I'm only licensed in CA. Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
It is correct that the deadline for a Summary Judgment response is 7 days before the hearing. The response must have all the evidence you're relying on attached to it, in the proper form. I do not recommend that you try this yourself. Contact a lawyer immediately to help you.