Can people please give me advice on having 2 under 2?

I have an 18 month old and her brother will be here on the 11th. He was a birth control baby soo a complete surprise! I wanted at least 3-4 years between my children. I have been having extreme and I mean extreme anxiety over having 2 under 2. To the point where I cry sometimes because I know how hard it’s going to be. My daughter is already a handful so I have no idea how I’m going to be able to cope with having children only a year and a half apart! If anyone has or have had two under two please give me some tips and advice on how to handle it and maybe some encouraging words. I’m trying to be excited for my sons birth but I can’t with my bad anxiety.