The fact that you are in foreclosure won't affect your citizenship application. You might qualify for a fee waiver if your household income is under 125% of the poverty guidelines. USCIS has these guidelines on their website so you can look to see where your income falls: http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=516e0cff46e21310VgnVCM100000082ca60aRCRD&vgnextchannel=db029c7755cb9010VgnVCM10000045f3d6a1RCRD. Finally, look into whether there are any non-profits in your area who do citizenship workshops. These are available in a lot of cities, and they usually only charge a very small fee to help you prepare your application.
The information offered is general in nature and not meant to be relied upon as legal advice. No client-attorney relationship is created through this information. Please consult an attorney prior to making legal decisions.
If people in your household (living with you and, usually, related to you) are receiving public benefits like food stamps, then you very likely qualify for a fee waiver. You would complete the form I-912, check the box for receiving public benefits (only that box), fill in the short little table right below it, skip the other parts, sign the last page, and attach proof of the current receipt of public benefits.
If you are concerned about doing this on your own, you may want to consider participating in Citizenship Day (free event sponsored by American Immigration Lawyer Association where you can have your application prepared for free and reviewed by an attorney - you can get advice from the attorney, too). The coordinators for Citizenship Day are listed here: http://www.aila.org/content/default.aspx?docid=25027
Contact the one for South Florida if you are interested. Best of luck to you and your family.
I agree with my colleagues. You should also reach out to your local legal aid, such as Catholic Charities Legal Services, they may be able to help you with your application.