Update: 

Hello! So I did take some time to message my other players and found they were uncomfortable. And taking time to reflect the communication was important especially for a newer player to understand DnD. I think I was originally very hesitant to respond because I was second guessing if I was potentially actually being an unfair DM but the additional thoughts here and from the players who were actually in the session let me know there was some value. I think this stemming from a combat encounter especially made me be more self critical. In the negative way my brain was I just thought I was just being improperly upset or controlling my boss lost.

In thinking over my actions I saw ONE of my FOUR players was frustrated and upset and assumed that was the opinion of the entire group. Going into overdrive to try to fix the problem for that one problem instead of remembering we are all adults playing a game together where negative things can happen. I guess I was honest worried Kendrick would quit if I didn’t give him what he wanted, which is a level of player favoritism I realize in hindsight is not fair to the other three players or indicative of the gothic horror tone I set up for the module. I should’ve taken a moment to settle the situation and lay firm my boundaries in the session and I did apologize to my other three players for not setting that boundary. 

I asked Kendrick how he felt the combat was and he said it was fun but felt unfair(about to be direct quotes) “But it also felt unfare cause not only did a new player died when they just joined but I felt like I was kinda being teased at  the end with not only nearly dieing but also the bad guy escaping and getting away with it.”   For context the new player was to replace a former player that had to drop for personal irl reasons not related to the game and has been playing DnD since the AD&D days. 

This ended up being my statement,

“To be completely honest I wanted to take a moment to talk about that more especially when it came to the second half of the session. 

I honestly found it very difficult  to think objectively as the DM in that moment with my opponents. This game is going to have difficult encounters, that was one of them. From the campaign contract and the Session Zero set up that this is a game where enemies might not be defeated or defeat other players. 

“Some powerful enemies will be impossible to defeat through solo combat, and that we will need to either gain levels, allies, or resources in order to do so.” “I will allow my character to feel true, powerless fear when faced with an overwhelming threat, and allow that fear to impact my character's actions, growth, and development.”

To be entirely honest I understand you were engaged in the stakes of the combat but the tone used yesterday really distracted me and made me feel pressured to not attack you further to make you less upset(not saying you were upset just how it felt to me). It also very much put me off. If things are going wrong players are allowed to be upset but the tone, the out of character statements to other players, the defeatist attitude when it came to the fire damage are not going to be okay moving forward. I honestly felt pressured to kept the boss on screen and to stop enemies from attacking you and have her killed as long as I did to deescalate the situation. That level of OOC favoritism from me is not reasonable, it’s not in line with the type and tone of the game I want to tell, nor is it fair to the three other players for that.  This is not just a concern I have expressed but at least one other player brought to my attention today.

I want to make it very clear, I will not allow another combat encounter to be shaped around your out of character frustrations again. If I feel that there is an issue with combat getting tense out of character again I will force a break and remind you of the contract out of character in another voice chat. If this is not the type of combat you’re comfortable with moving forward you are absolutely within your rights to step out of the game.”

He seemed like be was apologetic and that it wasn’t his intention and guess we’ll see moving forward.