being both a realtor and on a HOA board I can telly ou that there should have been a protocol they followed. You should have received a letter about your delquency first. Then they should have sent you a letter informing you that you have X days to either pay the balance or call to work out a payment plan. If you did not respond by that date they would have informed you that they are placing a lien on the property.
Since you received the lien letter...you are now responsible for the attorney fees, court costs and back HOA dues. I recommend you write a letter explaining your situation and a reasonable affordable payment plan you can make. the HOA board should accept it.
If you ignore it the HOA board will have the right to file a foreclosure against you on the house. Literally they can take your home for back HOA dues. You still would have time to work out a payment plan but then your costs will be triple what they are now; and they probably will want a more aggressive payment plan.