How do I get my husband to pay half of my marital debt if we divorce?

Yes, sounds like you will need an attorney. Property and debt division is required during a divorce. If you both are not able to reach an agreement, the court will ultimately decide the matter at trial. As to student loans and divorce, that is not always viewed as 50/50 marital debt. Each case will turn upon the specific facts including what degree was obtained, the income before and now of each party, what the loans were used for (tuition only or also living expenses), how long you were both married, the division of other assets, and on an on. You can see how each case could come out differently with different facts/answers to these factors.