Asking him

So my partner and I have been together nearly 4 years, we have a son together and I'm currently 31 weeks pregnant with our daughter, weve and throigh alot together, with me being diagnosed with two different medical issues, hes taken the step dad role on himself to my 6 year old son I didn't make him and my son decided himself he wanted to call him dad now, ive been with him since his lowest just after he lost his job I encouraged him to become self employed there's there's much to our story even bad things but we've manged to come out of everything together and stronger, so.. I decided that I was going to ask him to marry me Christmas day buy im so nervous, I've wrapped the ring up and was going to put it in the tree and put a vest on our son with it saying daddy will you marry mummy, so scared and nervous he'll say no 😫 wish me luck 😬