Sex life - masterbating

My bf and I moved in together (5 years dating) and idk I feel like he doesn’t find me attractive anymore. He went soft when we tried to have sex this morning and it just made me feel sad. He jerks off himself and watches porn, I don’t really do anything like that for myself…. And I’m thinking about doing it but idk where to start. I’m so embarrassed to say this but I’m 28 and I never really pleasured myself at all. I’m nervous and feel like it’s wrong… where do it start?