You got a lot of good advice. I hope it is helping you. People are saying a lot of the things I wanted to tell you:
This is a VERY difficult time for any mom, and it will pass. (as a mother of 10, I would agree that having two little ones was the hardest time ever)
Shower that little one with love in unconditional ways--make sure it's not only when she is misbehaving or when she is behaving. Asking for her help with the baby (go get a diaper, throw one away, bring the blanket, wiggle the baby seat...) is a powerful thing for her well-being, too.
Make sure you are accepting any help available for yourself. This culture is horribly stupid when it comes to respecting the post-partum period. You need a lot of support and special care for several weeks after having a baby. In many cultures it would be unheard of for you to be trying to deal with your toddler and the needs of your baby right now.
But I don't see that you are getting advice on actually changing the behaviors that you "don't tolerate". It looks like you are saying that you can't tolerate them, more than that you don't. I don't mean that disrespectfully, I just think that as parents we sometimes don't see that we don't really have a plan for changing our child's behavior or we are not sticking to it if we do. So the result it that we actually DO tolerate the behavior. You probably already knew (or have learned) that yelling doesn't change anything. I assume you are yelling because you can't help it, not to try to change her behavior. That's okay, as long as you don't think it's going to help. I say it's okay because it kind of has to be, doesn't it? After all, we are going to yell sometimes. Anyway, create a plan that does these things:
Narrows the focus to one or two behaviors to focus on. It may be as broad as obeying all direct instructions ("If mommy tells you to do something, you HAVE to do it") or as narrow as not saying a certain word.
Matches an unpleasant consequence to the behavior. This must be something that she really dislikes enough to avoid. I have never seen time-outs work at this age (although I do use them to halt a situation and give myself time to think). The vinegar idea sounds like it may work. She may lose a privilege (though my 3-yr-olds don't really have many of those in the first place and it has to be something that she is already accustomed to having, not some new promise that is then taken away). In our house, we do use spanking for this, but it is a very deliberate part of the overall plan and only implemented where it belongs in the plan. It is kept to a couple of short swats, often over a diaper, very light on the touch and heavy on the talk. The point is that they do not want to repeat that experience.
Assigns the consequence EVERY time that the behavior in focus happens. The fewer times you let it slide the sooner you will be done with this behavior. This is part of the reason that this is the toughest time to parent. Sometimes you just have to be "doing the baby" and can't get away to catch the behavior. But keep with it.
This long explanation may make it look like this training is the most important thing on your plate right now. It really isn't. It's just one more thing to help you feel better. Having a plan that you are putting in action keeps you from feeling that "cornered" type of frustration and may cut down on the yelling. If you find that you could actually tolerate her behavior, knowing that you will work on it soon (in a few weeks when things are going more smoothly with the baby), then do that. Whatever brings more peace to today.