I can really only answer generally, as there are a lot of factors involved in this matter. For instance, I can't tell from your question whether he filed for divorce in Texas or in Missouri. Regardless of where the suit is filed, you HAVE to be given notice by way of service. I can tell you that in Texas, if one party wants a divorce, then the divorce WILL happen. You don't have to sign anything. If he files suit and you don't answer, then he can get a default judgment. If he files suit and you do file an answer, then you get your day in court... or at least an opportunity to come to an agreement regarding property and/or kids. For that reason alone, I highly recommend you retain an attorney and respond to the petition. But the divorce is going to happen. Best to be realistic and protect yourself. Good luck!
I agree with the other attorney -- you did not tell us what state he filed the divorce!
If he filed in Texas, a divorce is not "magically" automatic in 90 days! Something has to happen - you have to sign some paperwork & he has to appear in front of a judge and read a statement.
I have no idea what happens in MO!
If you were served legal papers then you need to ANSWER the divorce paperwork. If you do NOTHING then he can get the divorce done on a DEFAULT basis. This could be very bad for you!
I suggest that you hire an attorney! Trying to represent yourself is usually a bad idea since you do not understand the law (of course not - you did not go to law school!) and you don't understand all the details.
It sounds like he is bluffing but I won't swear to it!