You are likely only to find HELOC's directly from banks at this point in time, some banks still allow mortgage brokers to sell their HELOC's, but I'd still recommend you deal with banks as the fees will be less than if you go through a broker (they are more of a "complimentary" loan program for brokers to offer their clients when the situation warrants them, rather than something that brokers concentrate on marketing).
Like I tell everyone, if you have bad credit and are applying for a mortgage you first need to know exactly what is on your credit bringing your scores down, when it happened, if it's owing, paid, etc. as well as what your credit scores are. If you don't know that information then you'll be operating in the dark. You can get your credit reports from https://www.annualcreditreport.com/cra/index.jsp and you can get your credit scores from http://www.myfico.com/ - once you know that information you should be able to approach any lender and say "This is my credit situation, these are my credit scores, do you think you could work with me?
I just saw this post after answering your new question...
When you say you have bad credit, sometimes your meaning & the bank's meaning of bad credit are different. Your credit may be good enough to secure a second mortgage. You may want to start by asking your bank about a second mortgage. They should be able to give you an answer in a couple of minutes.
By the way, I am so sorry to hear about the passing of your husband. I know it must be hard.
I would love to hear about the outcome. you can contact me at firstname.lastname@example.org