Contacts that arent mine on iPhone?

Ok well this was a while back but it's still happening and I never did anything but now IIm getting fed up, ok well me and my ex i don't know what the deal was like I put his iCloud on my phone to find his phone and to download stuff from his phone but somehow they got linked and mind you this was in like January and I told him twice to take me off his iCloud that his contacts pop up on my phone and he said he took me off which I believe him he has no reason to have me on there, but when I try to text I ll type a letter on the top message bar and my contacts will pop up but so will his and I have no idea how to get rid of it and my ex is not the brightest he doesn't know tech all that much and this is his first iPhone which is a 5c and mine is 5s if that helps in any way but please someone help I need to just have my contacts on my phone

You synced to your ex's iCloud, therefore you would get all of HIS contacts, mail, etc. To fix, delete all of the contacts an sync to your own iCloud, or make an Apple account.

I have my own iCloud and I'm connected to my own