Married man hitting on me

Hey all so this has really disturbed me...I have a daughter and my babysitter and her husband helps me out once in a while when I wanna run errands....my babysitter always text me from her husband phone (idk why) so his husband started texting me and being flirty so I told him not to text me such stuff and he should stop.This has really disturbed me why married men do that and got me thinking if I really wanna get married.should I tell his wife thankyou all