iCloud email hacked?

im not sure whats happening here but ill explain, i think someone with the same first and last name has been using my iCloud account. i have received emails from people i do not know and from social media accounts that she has created... is it possible she may have logged into my account by accident? there are emails from other people with the same last name (presuming her family)... i have been logged into this account since i got my mac book and never logged out of it, sorry for the long question but can anyone help? Thanks