Afraid to masterbate with him here

I live with my bf and he pretty much has no interest in sex anymore. He turns me down all the time. Rarely he will do it but it's only when he wants it. So I'm obviously sexually frustrated. I want to masterbate, like when he's in another room, but if he were to walk in and see me I'd probably be mortified. I would feel super pathetic and like creepy idk. I have no problem playing with myself in front of him when we are doing foreplay and stuff but this is different. And I know he would not care to join in. How can I get over my fear of him seeing me masterbate?