Difficult friend

Hello ladies I’m looking for a bit of advice. My best friend is pregnant with twins, as excited as I am for her she’s becoming too much. I’m currently in the middle of a cross country move with my husband and son, looking for a house to buy, getting ready for my new job, planning my son’s birthday, and helping my husband with tying up loose ends here. My friend wants me involved in everything with her pregnancy; helping plan the gender reveal, helping plan 2 baby showers in 2 different states, helping with the nursery and setting up her house, helping her move, and just a bunch of small things. I’ve told her the things I need to get done for myself but she still is constantly trying to pile so much on to me, how do I tell her nicely that I can’t be involved like she wants me to? I’m already worn thin with my responsibilities, I can’t add on everything she wants and not have a break down.