I need some advice

So my boyfriend and I have been together going on three years now and since we started having sex, I’m terrified of giving him a blowjob. I don’t know why I’m so worried over it. Don’t get me wrong, I’ve tried, but I just can’t get over the precum come out at first and I swear I’m gonna puke all over him. I guess it weirds me out🤷‍♀️. Anyway, I want to make him happy and he swears I don’t have to do it to make him happy as long as I’m with him (☺️), but it still makes me feel self-conscious because I feel like I’m the only one that don’t like giving head.

Anybody got any ideas how I can get over this?