Would I be awful if I backed out of planning a baby shower?

Some details: the baby shower is April 4th. The mom to be is a coworker.

I used to be friends with her, shes always been a little bit selfish but since she got pregnant it has gotten way worse. She and her boyfriend started trying around the same time my husband and I did and I like 95% positive they only started trying because we did. Well she got pregnant and we still have not. Since she's gotten pregnant she has turned into an awful person to be around. All she does is complain about being pregnant and has said some shitty things to coworkers about how I'm jealous because she got pregnant and I can't. At one point I took some overtime that she wanted but told my boss that she would only do if no one else picked it up. She didn't tell me that she wanted it. She was pissed about it but instead of saying anything about it to me, she complained to my coworkers about it and said that it wasnt fair that I wouldn't give it to her because I don't have kids and she needs the money for the baby. I'm only planning the baby shower because I felt bad and couldn't say no because she gave me some sob story about how her boyfriends sister wasn't going to give her the day she wanted. The comments about me happened afterwards. Shes done a lot more stuff that makes me mad since then so like it's gotten to the point where I really can't stand to be around her. She only texts me to complain about stuff. If I text her about something I get a generic response or no response at all. I've been home with the flu since Wednesday. Something happened at work either yesterday or Wednesday that everyone knows would be a big deal for me to have known. Today something else happened that had to do with that and another coworker called to let me know. She said that the pregnant coworker came to her car and let her know before she even went in. The other coworker asked her if she had let me know and she said "no. I'll let you do that." But she texted me several times over the last few days to complain about other things. Today she texted me to complain but they were literally one word texts. I know that's not a big deal but like I've been tired of her for a while and she just keeps getting worse. It was already going to be hard for me to plan this shower since I figured I would have been pregnant by now. But it's to the point I just want to be done with her. There is still 7 weeks to the shower and it wasn't just me planning it. It was me, her mom and her boyfriends mom, but her boyfriends mom backed out last weekend.