Do not sign it without consulting a lawyer. You may be eligible for either a pro bono lawyer through the local bar association, or from Legal Aid, online contact at: http://www.mdlab.org/
Once you give up your titled ownership, the other owners can sell the property and you would have no rights. Is your husband being taken off the title as well? If the refinancing is needed to save the property from foreclosure, then the new mortgage company may insist that all owners be on the mortgage. If your credit prevents the refinancing because of qualification requirements, then you may be able to protect your rights to the property by executing a separate agreement with your father-in-law (and husband if he's remaining on the deed), but it would have to be recorded in the land records to protect you. It is possible, however, for a person to refinance and be personally liable for the mortgage, without all other co-owners being personally liable for the mortgage. Accepting $2,000 sounds like they are attempting to "buy you out" and will use that payment as a basis to argue later that you sold all your interest in the property to them.
If your father-in-law has hired an attorney, it sounds as though there's more going on than a simple refinance. Can your father-in-law refinance without you? He may be able to qualify for a loan on his own and the lender may be willing to accept a promissory note from just him, however, if your name is on the deed, the lender will require you to sign the deed of trust which gives the bank a lien on the property. If you sign the deed of trust but do not sign the promissory note, you are not personally liable for the mortgage. However, if the mortgage is not paid, the lender can foreclose on the house.
This should not be construed as formal legal advice or the offer of the formation of an attorney/client relationship. There is no substitute for taking the time to consult directly with an attorney regarding your specific legal needs and issues.