Im really sad

Hey all, am gonna talk quick about my issue, im married and pregnant and me and my husband have sex once a week cuz he thinks that he might affect the baby or smh, anyway whenever i leave out to collage or to my mums and he stays home alone, “ he masturbate” how i know is that i find the oil position is change and he changed his pants with a dry cum on it!! He thinks he is smart tht i wont know , I tried once to talk about this HE DENIED ANY OF IT!!! But i feel bad like why would he do such a thing am i like not enough for him or wut!! I feel like im going to cry in any moment and i hate him and i feel disgusted... can anyone tell me am i wrong or what!! Btw i spoked once with my dad about this thing cuz he is a man and he knows he told me never to discuss this thing with my man because its like disrespect for a man to embarrass him like tht ..