Nevous

So I haven't been in a sexual relationship with a guy yet (I'm the abstinence till marriage type), but me and my guy are unofficially engaged so I'll be there soon. But I'm super nervous about having sex and doing any sex things and the idea of givin a guy a blow job superly grosses me out. Like a lot. Is there a way for me to get over that? Or what can I do to not freak out about it all when it's time?