Divorce?

I've tried to do research on this, but everything I find says something different.. SO and I have been together for 6 months. They've been seperated for 10. We live together and everything. He's been struggling financially for awhile and was just now able to file for divorce maybe a month ago? Well, we got the papers and tried to get her to sign but she kept being wishy washy for three weeks straight, goin back and forth saying she would sign them and then that she wouldnt.. so about two weeks ago, we went to have her served. Thursday, March 2nd is the day I'm assuming she got served because she asked him about it. Court says she has 20 days to respond after being served.. What happens if she doesnt have an answer within those 20 days? Ive also read that when you have someone served, it will take even longer, so about how long are we talking.. We live in Texas