my step dad has dating apps should I tell my mom?

OK so my husband Bought my stepdad a phone because his phone broke He doesn't know how to transfer all his apps into his new phone So he came over dropped off the phone He didn't stay because of the whole virus thing he put the phone outside While we were setting up his phone transferring everything into his new phone we found 2!!!! dating apps I waz very upset I went through the apps He is looking For a new girl He's been married to my mother for about 10 years now By the way she left my dad for him That night I couldn't sleep I was very upset the next morning I called my brother and told him He was not surprised at all he said that is completely normal all men do it and it's actually good for their relationship 😦 I was very upset by his respond He told me very clearly do not get in it do not say anything My mom has some health problems She has heart disease He thinks by me telling her she might get really upset an get heart attack oh and 4 years ago he wanted us to fix something in his phone and we saw that he was paying for sex i doing say nothing to my mom Because the next day he got into a horrible car accident he almost lost his life It was just not the moment to say anything time went by in a letter go But here we are again im mad hurt for my mom i don't know what to do