Poppy2133, it shouldn't cause you any trauma at all once your little one goes off to pre-school/nursery.
Before our ds started nursery, our family were saying "You'll be the one crying outside the gates, it'll be really hard on you leaving him after so long..." etc etc, I just said, "We'll see." I knew he was going at the right time for him and because he was confident, we both felt nothing but pride in seeing him settling in so happily. It wasn't in the least bit traumatic, and I didn't feel even slightly emotional, only extremely proud. So [thumbs nose at family] emoticon!
The thing is, looking after a child as an isolated stay at home mum, it is extremely hard, especailly when they start going through various phases (age 3.5 to 4 is particularly stressful). But seeing how your child develops under your own wing with your love and guidance, makes you proud beyond words.
Believe me, poppy2133, you'll relate differently to your son as he grows and reaches the age when you think he should start preparing for a gentle separation from you. As poppyseed said, you don't need to follow the crowd and put him in nursery just because everyone else is.
We put our ds in nursery to prepare him for school, and not just for the sake of it, but he wasn't really ready for it any earlier, and I wanted guide him through his difficult phases myself, without picking up any further behaviour issues from anywhere else! Sorry to say, but that's what happens in nursery, just in the same way that he'll start bringing home coughs and colds, he'll start thinking that spitting on the floor is a great idea "because X child does it"!!
As far as I'm concerned, I found it quite easy to make friends with the other mums once my ds started nursery, but then I try to chat to other mums in the park, playgroups etc but I do find it hard to find the time to commit to proper 'regular' meeting up type of friendships, as I work from home as well.