Just meed some advice

I've been dating this guy for about 1 year 4 months and i totally love him but I can't see myself marrying him one day my parents agree and he hides a lot of things from me i went through his fone the other day( the left his phone and i knew he's password bc he's predictable) so i went on it just to see something told me to look at it i came across a WhatsApp where a girl is sending him nudes i talked to him about it he asked for forgiveness and i gave it the worst part is it's my bday and she congratulated him and said I'm beautiful (Even tho she knew he's dating me)and say he sould tell me happy bday😔and every year it's a total f-up and he knew it and yeah i haven't even met his family after all this time what should i do ? I really need advice 😭