how can i verify that i signed a document that I don't think i signed on a contract that is outrageous

I clicked on an email about an apple pay terminal that said no annual fees and so much per swipe.  I started filling out the form, then thought to myself, how do I know this is legitimate.  Then I received this card reader in the mail, (in which I don't have a store, I was planning on starting an online store.  now I'm being charged 72.00 per month that started out small and gets higher each month.  They claim that I signed some document and I said I didn't and that they kept sending emails asking me to complete the application and leaving messages on my phone.  Now they are telling me that I signed this document and that there is a minimum fee per month.  I told them to cancel it then because I can't afford to have something that I have no use for to begin with.  The way the email described it, it was similar to square.  When I asked to cancel, they told me that it was a $399.00 cancellation fee.  I told them I could not afford that and that I was disabled and reason I thought perhaps I could sell handmade cards and crafts online.  I started looking through my computer, and there is a copy of this form before I finished the application.  How is this possible?  I looked under digital signatures, in which I do have one now after July 22 to sign real estate papers.  Prior to that, I had no need to digitally sign anything.  This company claimed to have sent emails with a link on where I could review my account.  After all of this, I'm a little afraid to do that.  How can I tell the authenticity of the document the guy emailed me saying that I signed this contract.  I told him I would be crazy to sign a contract of that nature not having a store, DBA, nor tax and sales use permit.  I'm also going through a divorce.  I'm disabled, and don't spend a lot of time on the desktop, so I forget to turn it off a lot.  The forms I started filling out looked nothing like the contract he sent.  I always print the web pages that I make purchases on as well as other pages to read in the recliner because my feet swell if I sit at the computer very long.  He also emailed and affidavit for me to fill out and told me to also file a police report.  I could barely walk for 3`4 days and had a dr appointment, divorce papers to prepare, and still need to contact the tax office.  Now I can't sleep, because this is bothering me and I have zero funds in my account and bills left to pay.  Is it possible for them to have collected my bank information from my computer?  I had to change the code on my modem as well because it would flash when nobody was using it.  I don't know why they would state on the forms that your application would be pending approval, yet approve this contract with someone that did not have a company.  And by the amount the fees are, I wouldn't make a dime.  I told the guy that I would use paypal or square that have not hidden fees or minimums.  Please help with this matter.  Stress does not help my situation at all, and I am stressed out waiting for automatice payments to start hitting my bank account and the overdraft fees to start kicking in.  That adds up quick and I live an a smaill income as it is.

Thanks for any assistance I can receive.  This place sounds crooked to me.  They go by about 3 different names.

Sincerely,

Cynthia