oral...gross...😖

So I hate going down on my SO even though it's one of his favorite things. I always feel like I'm choking, gaging and that after I'm going to throw up (which has happend, I never told him that though). I do want to please him. How do I get over and passed this? Every time he asks I panic and just shut down even when he's just joking about it. I hate everything about oral and I'm also not good at it obviously, no matter how hard I have tried. I love to pleasure him. I just can't get on board with oral. Pointers?