How to talk dirty to my boyfriend

I'm an awkward person when it comes to talking about sex. Probably because we avoided talking about it in my house and I went through a sexual assault when I was younger. My boyfriend is an amazing man, my best friend, and the love of my life. He's helped me feel more comfortable in my own skin, and with our sex life. Recently he's been wanting to incorporate talking dirty. He doesn't try to push me, he'll just starting guiding me through something and then once talked about me talking dirty back one day. The thing is...I don't know how. I get embarrassed and don't know what to say or how to be sexy. I know he's sexually attracted to me and enjoys what I do for him, but I'm nervous about it. Does anyone have any tips?