stalking, remote access my device

someone (estranged husband) has his lover stalking me for over a year i cant lock him out of my phone because of his allowed devices on his samsung (newest A13) how's can allowed even though im under his acct the iph in myname,please he's github developer how can they access my iphone remotely when i called they told me this couldnt happen his lover has all my personal info and is impersonating me?!!!!!!!