Being a writer means making a lot of decisions, hard ones. You're going to have kill people, traumatize others. Someone is going to have to lose. You're going to write things that people don't like, sometimes. When it comes to making decisions as a writer, you have to be firm. You have to stand by your guns.
Ready, Aim, Fire
I like to make all my decisions right at the beginning of a book. This is why I create an outline. Once you decide who's going to die and who's going to fail and which heart is going to get broken, you need to stick with those decisions. It gets harder to do that if you're writing a series and you begin to develop attachments to the characters. It gets more difficult as readers form attachments to those characters. But as a writer, you stick to your guns.
"Stick to your guns" is a bit of an old-fashioned expression that simply means you stick to the decisions you've made. Don't change a character's fate or alter your story, unless you want to do it. It's very easy to be influenced by readers and by other people's opinions. Don't be. Usually, your gut instincts and your first decisions are the right ones. You may get to questioning yourself and end up talking yourself out of a decision.
If you're really struggling with it, try it both ways. Write that scene, or that chapter, twice. Do it once with your original decision. Re-do it with the new change you've been thinking about making. Now, read. Put it aside. Go live a day away from it. Come back, read again. Make a new decision based on what you want to do...and then stick to it.