sneaky

My boyfriend keeps deleting messages from my phones off his ex he says there not nice that's why he deletes them! He uses my phone as he refuses to have one of his own!! They have a 4 year old together that she uses against him as a weapon she's very twisted and jealous and would do anything to cause trouble !! She text yesterday saying her current bf is now his new step daddy!!! And for my bf to stop calling her of his bosses phone at work and to stop turning up at her house? But he doesn't tell me he rings her from work an ive cought him out turning up at her house before an lying to me he swears he loves me an tells me everyday loads and we have sex loads everyday !! Should I be concerned as we're trying for our own child pushed by him ??