The fact that you are receiving these SPAM messages from several different of your contacts suggests to me that your account may have been compromised and information about the people (your contacts) obtained from it and the hacker is using that information to generate these messages. I'm not sure if or how this occurred or if the connection is still active - it could be malware or a someone may be actively connecting or it could have happened at the email provider's servers - we don't know enough to tell at this point.
While it is possible that they all
are infected and sending false messages (possibly through e-mails sent to them that appeared to come from you), I find it unlikely that this suddenly and simultaneously occurred to all these different people (though it is of course remotely possible - especially if done using messages appearing to come from you). A hacker could simply be sending out the spam using their email addresses (possibly obtained from your contact list) without their knowledge or without their systems even being affected. We can address the possibility of infection and compromised accounts at a later stage (both with your machine and theirs) - but for now I'd appreciate a reply to the inquiries in my first post so I can more fully understand the situation and provide better options to consider.
In the meantime, please download, install, update and run a FULL scan using Malwarebytes: http://www.malwarebytes.org/
(use the free version) and delete anything it finds.
Thanks and good luck!