The new baby should have a present read and wrapped to give you toddler in hospital.
His whole world will not be tipped upside down, honestly it won't. Get him to help, pass a nappy, muslin, that sort of thing, then he will feel involved and helpful and a big boy.
There is bound to be be a bit of grumpyness and jelousy here and there, but don't make too much of it, totally natural. Just cuddle and reassure him that you are there for him as always. It will be hard, but try and have some time with just the two of you, even just watching TV on the sofa together for one Peppa Pig (you can shut your eyes!).
Tis so cute when you have two, they are so cute together and piss each other off. My eldest DS once pushed his baby brother in his baby boucer into the kitchen and shut the door as he was too noisy just shouting and making baby noises. I'd gone for a quick shower, no harm done to either child.
It's daft to feel guilty, although I do remember feeling a bit sad that it was going to be no longer just me and him (and DH too) but then this whole seam of love you never knew you had opens up and you love them both so very much. Plus, if I do say so myself, they adore each other, two boiys aged 5 & 10 currently snuggled together under a blacket with popcorn watching Ice Age 4.
Wishing you are well.