Help!!

My mom is planning a baby shower for my sister in law who accidentally got pregnant and I'm trying to help while secretly battling fertility issues for 2 years no one but my mom knows and I can't help but get sad everytime we are working on stuff and have no idea how I'm going to pull this off I'm already fighting depression and everytime I trun around its more about this baby even as I right this is feel selfish but I don't know what to do but run and hide from everyone all the time and that's really not helping 😢 all my mom does is talk about her first born grand child (my husband has a child from a different relationship, she still treated as my very own) OR my sister in laws pregnancy or doctor appointments and when I tell her to please stop she just gets mad and keeps doing it I'm fighting this fight alone and I just can't imagine how I'm going to handle the next 2 weeks of planning and the shower it's self I want to make it perfect for my sister but 😧