It may not actually be coming from your account. Spammers can and do spoof email addresses that are known to be good. Best way to determine that is to have the persons receiving the email check the message headers, or run a message trace to determine which IP address the email is coming from. If it's not coming from Microsoft, then someone is simply spoofing your email address.
How the person receiving the emails can check the message header depends on what email client or service they are using.
To do a message trace: http://www.wikihow.com/Trace-an-Email
If you suspect your account is compromised, try making sure your version of Chrome is up to date, and disable all add-ons and plugins except for those you absolutely need. Check the Sent folder in your email account and see if any of the emails are appearing there. If they are, then your account has been hacked. Get in touch with Hotmail/Outlook.com about remedying that.