Divorcing. How much of his IRA am I entitled to in Texas.

I filed my divorce petition pro se this morning and have a concern. My husband and I have been married 3 1/2 years. He started the job he has now 3 years ago. Every month the company takes a certain amount from his paycheck. I had an IRA when we married, but cashed it in to pay for the wedding.
He gave me 4000.00 when we seperated and told me that should cover my part of the IRA. I then found out the IRA is over 20,000.
I am a college student and have been for the past 4 years. I am trying to finish my five year degree this year. I am not asking him for spousal support or anything else, but the District Clerk said I was intitled to half of the IRA, and that I could file an amended petition within 9 days. I am visiting with a lawyer this weekend, but I wanted more than one opinion. Since my husband gave me 4000.00, how much of the IRA should I ask for?
1/3 or 1/4 or is 1/2 still mine? I dont want to take him for everything, but he ruined my life and I need this money to live.
Any information would be very helpful.
Thank you.

He ruined your life and you want to be nice.. See the attorney and ask to get everything you can.. if the IRA was started during the marriage then you are entilited to half.