a secret in why he cant touch my

my online lover now boyfriend we had sex last night. how do i tell him i have lumps in my breast and that's why i dont want him to touch them or suck them. he thinks i just don't like them and bc one is bigger then the other. its really hard for me to even admit it to myself but to another person its hard and he seen me naked b4 u send him nudes so he seen everything b4 we even had sex.