WEIRD CREEPY MESSENGER HACK? AM I IN DANGER?

Country greece. I have a phone (lenovo k6 note) that i bought recently. Its a dual sim and i have 2 numbers, a new one that i got as a gift with the phone from the store and my number that i use 3 years now. I have a facebook 8 years but in facebook i have a number i had a long time ago that now i don't use and i think is out of use.

I was on my phone and got a notification that said
The phone contact argi is now on messenger. From what number? I don't have such a contact on my recent numbers or ever! Not on the previous number either.
The notification was suddenly gone and i found it again at the notification history. I clicked it and it opened a messenger contact *argi* . I clicked details and there was no "see profile" or anything. No profile? Contact i never had? And it said you added the contact 17 June 2017. Thats today. Something i did not do.
What is going on? I blocked the contact from messenger so it can't send me messeges and changed password on facebook.

I can still find the notification on my phone and when i click it i can still open the messenger contact. What is this? I don't want this contact and i don't know what do to. Will add pictures. Ask for more info if you need.

You were Not Hacked that Contact came from your Contacts Facebook Messenger Scans through your Contacts and finds people to add as Contacts on there it does not actually give out your Phone Number or any Personal Information

Yes, delete your account immediately