Not sure about this

So I am 17 almost 18 and I have been dating my current boyfriend for nearly 4 years. I know I love him and I don't regret anything we have ever done so far. That being said, I know sex is coming and idk if I'm ready for that. I know it sounds crazy but I just can't decide if I'm ready. It almost happened one time and I completly freaked out and cried. He doesn't pressure me but I feel like after all this time I shouldn't even question it. I do go to church and I feel like part of what is holding me back is the fear that if I dd I would go to hell?? Idk I'm just a nervous wreck and I was hoping someone in a similar situation could give me some advice. Thanks ahead of time (: