We’ll talk about what you describe as an “obscure law,” a bit later. What is more likely, however, is that you need to look at the loss of your use of the family home as part of the “bigger” financial and custody picture. What’s not clear is whether or not you are legally separated or filing for divorce. You can, for example, file for “limited divorce” in Maryland: http://www.courts.state.md.us/faq.html. In that process, you can raise issues about being owed “rental” income.
 
There are also important factual issues, regarding how you left your home. For example, you specifically said you were “forced” to leave. This is far different than someone who simply decides, for convenience sake, whether to stay or go. Evidence of being “forced out” could be substantiated by the fact(s) you had to leave personal possessions behind, that you had no definite place to go when you left, and that you were in fear of being harmed. If you can, get evidence (receipts, or even a calendar of dates, witnesses) of these facts. They will tend to support your husband has financial obligations for your leaving.
 
Have You Started A Legal Process?
 
It’s been more than a year, since you separated. But there are types of separation in Maryland, too. Given the issues you faced, with allegations of mental cruelty, here’s a link describing these types of separation, and an advocacy group that may be able to help you…http://www.ftmeade.army.mil/ pages/sja/leg_asst/sd_factsheet.pdf. Since they also give counseling services, the site may help you establish the psychological claims (by using their counseling services) you made.
 
What About Your “Obscure Law” Question?
 
I know people do find some old laws on the books that settle a question. Though this is not meant to be a final answer, I did spend some time researching Maryland state laws on rental agreements between spouses. I didn’t find anything exactly on that point. Still, even without that legal ‘technicality,’ you have definite rights when it comes to settling who owns and owes what, and who has a claim to proceeds from the other spouse’s use of the family home. This is especially true in what is called “constructive desertion”: http://caselaw.findlaw.com/md-court-of-appeals/1397447.html.
 
Generally, the Court will only be able to calculate sums owed between a couple, as of the date the couple legally separates. Here’s a case describing the priority of a court, however, of seeing that parents contribute equal portions (if not the same amounts) of their income for their children—which will include rent or mortgage payments: “a child should receive the same proportion of parental income, and thereby enjoy the same standard of living, he or she would have experienced had the child's parents remained together.” http://caselaw.findlaw.com/md-court-of-special-appeals/1417586.html. This could result in your being paid for disproportionately higher rental versus mortgage payments.
 
On the other hand, it’s not at all uncommon for couples who separate to reach a separate agreement, and the Court will probably accept that agreement. This is more likely when a couple is having some grounds of agreement about dividing assets. In your case, it sounds as though there is a real potential for great disagreements. In this situation you should certainly try to get professional advice as soon as possible. Based on where you live and your income, you might be eligible for low-cost legal services…http://www.mdlab.org/.
 
You may also try to get the separation/divorce process started by filing on your own. Here is an on-line legal library with Maryland family court forms you could use to start: http://www.courts. state.md. us/family/selfhelp.html.