Pissed and jealous that my fiancé’s ex wife is pregnant

My fiancé’s ex wife is in her second trimester and I know this community is supposed to be kind and everything but I’m so pissed.

She’s not even with the baby’s daddy anymore and he has 3 kids from his divorce already and I’m so mad because we are all already so tight on money and I know this is going to change everything.

And my jealousy and anger made me realize that I want my own baby. And I just know that her kid is FOREVER going to be a pain in my ass because our kids will be so close in age and all the attention and resources will be split. Because yeah— me and the ex wife do NOT like each other

*********EDIT:

Yes I know I didn’t explain everything and I’m sorry. Thanks to everyone for contributing. I’ve been dealing with this for a long time and I posted while angry.

It absolutely affects my life because my fiancé and his ex-wife share custody of their 2 kids. And I love his 2 kids. We have been together for 5 years and we spend so much time with them, so many memories. I love watching them grow up.

Now, the ex-wife is going to be a single mom with an entirely new baby which she will need help paying for and taking care of. She already works 2 jobs and still barely makes enough money to support herself. When the baby comes, the kids are probably going to have to get jobs to help their mom pay bills and/or babysit. So the kids won’t be able to spend as much time with us. This throws off our entire coparenting plan and the kids are going to be stressed because they have to help their mom out. It ruins everything.

After she broke up with the baby’s dad, he moved out and now there’s nobody to take care of their 3 dogs when the kids are with us. So we have to go to her place, EVERY DAY, twice a day, when she is working to walk them. Because usually the kids walk the dogs, but they can’t because it’s our days for them to be with us. I feel like this new baby is going to be like the dogs where we have to pick up the slack where she falls short.