Possible malware has accessed my phone especially fb

I have watched a few videos sent to me by somebody on messenger. They were not from a verified website, I watched the videos in the messenger app. A few were gifs, but not messenger gifs. 
This guy now seems to know an awful lot about me. What has happened and how do I fix it?

Hello Lex, 
Thank you for contacting AVG Community Support.
We understand that you are facing an issue on mobile device.
We're sorry to hear that you're facing this trouble, we regret the inconvenience caused.
We do have a specialized team who deals with mobile queries.
We have escalated your case to concern team and they will get back to you via email and help further.
Thank you and keep us updated.

Hello Lex, 
Thank you for contacting AVG Community Support.
We understand that you are facing an issue on mobile device.
We're sorry to hear that you're facing this trouble, we regret the inconvenience caused.
We do have a specialized team who deals with mobile queries.
We have escalated your case to concern team and they will get back to you via email and help further.
Thank you and keep us updated.