Help! Oral Advice please!

So my boyfriend has been asking if he can go down on me, which I'm curious about but idk, I feel so awkward about it. I've had someone go down on me once for like 2 seconds, which felt good but I'm always afraid they'll say something bad about it after? I want to get comfortable because I am curious and am willing to do it, i just want to know if any of you have ever felt insecure about it in a sense? How did you get over it?