Congratulations. I had dc3 at 43, ds1 was 7, dd was 5. Not a huge gap, but bigger than hoped for (mmc inbetween).
Ds1 and dd absolutely adore ds2, although he's the most 'spirited' baby of the 3, and is having the worst terrible twos, which show no sign of easing

some mornings can be stressful, as he can cause big delays getting ready, (wrong socks / t shirts you name it...) and he can be hard work when I take the older two to after school activities- they only do gymnastics / footy and both do swimming but he won't sit down and watch, so I spend the whole time exploring with him.
The best bit is watching the three of them develop their own relationships. I don't have as much time for one to one, and worry I don't give dc3 as much time to learn but dd has taught him to count to 20 herself e.g. .
It's certainly been harder than I ever imagined, with him being such a strong willed baby (so envious when I read on threads how dc3 just slotted in and was a breeze
) but I wouldn't be without him. And I absolutely would have loved dc4 if it wasn't for my age / finances / house size!