Hotmail account sending bulk messages and spams to my contacts

So here it is I have hotmail, gmail and yahoo email account and to maintain professionalism I use hotmail account for my job and university emails I have never used hotmail account to signup on silly websites or newsletters. but this morning I woke up and checked my yahoo account and received two emails from hotmail account which i did not send, upon checking those emails I found that those were spams with link to some other website. I never experienced such problem before with hotmail and didn't expect this kind of activity. Now I am embarrassed because all my professional contacts were sent those bulk spams and some of them are really professional people. I checked sent folder of my hotmail account and found that those email were actually sent from my account as there were sent messages those were spams with all my contact email addresses.