There are some good answers here. I wanted to add a bit. You already know the answer to your problem. You said it in your post: Set boundaries and maintain them.
How you choose to do it is going to be based upon your child's personality. It sounds to me like she is in desperate need of consistent and firm rules and boundaries, as well as loving and patient guidance. If you remain consistent (NEVER give in, tantrum or not), she will quickly know her place in the house. Stop allowing her to run things. If your answer for not being able to use the bathroom, do laundry, cook a meal, have 20 minutes to de-stress is "I can't because Angel will flip out," things need to change.
The change has to start with you, not her. She is not, I'm sorry to say, the problem here. If you are consistent and firm with her boundaries the tantrums will stop because she'll know, no matter how hard she tries, you will not relent.
Since this is your first child, I have to say that you must not allow yourself to feel guilty for teaching her boundaries. You can't feel bad when she cries or embarrassed when she throws herself to the floor. Children are easily disarmed when they do not get the response they are looking for. Don't feel bad. Just smile, calmly say "okay, well, I'll be washing the dishes," and walk away. I've seen one mother who couldn't hold back her laughter (it is pretty amusing to watch some of these kids freak out sometimes)...that laugh embarrassed her SON into stopping his tantrum!
Don't feel bad about the higher pitched screams which follow you. Guilt is what stops many from being good parents. You aren't supposed to be her best friend, you are supposed to provide her stability. She'll get the picture eventually. If anything, what you should feel guilty for is each and every time you relent. When you are inconsistent, your child's little world is chaos. It's scary never knowing what is acceptable! Think about it for a second: If you were told one day that you were allowed to do something, and then the next you couldn't...you'd get upset. You might even protest or debate the issue. It's simply not fair to expect your child to adapt to different rules without protest.
So, enforce the rules It will make her feel secure and happy, minimize tantrums, teach her better manners, and make you feel like a better parent. Remember, we're not raising children to be self-serving, rude people; we're raising children to be adults we can be proud of. With every parenting decision you make, consider the long-term effects.
Good luck!
C