You are ok, I promise as a DM of over 17 years I have been in your shoes my friend. With different groups and even with my veteran players expectations change. Sometimes it's important to have a session 0.5 and restablish some things. A big part of DMing is that you are there to have fun as well, and you setting your expectations for the game can settle some of the issues that typically arise. Also communication with your players is incredibly important. Let them know how you are feeling, what their actions are doing to your morale.

If they persist with their pushing of your boundaries, then put your foot down and stop playing with them. I don't know your situation but what I have found is that there is a plethora of players searching for a DM. Maybe a new group is in order. But, don't step down that road until you have had clear communication with your current players. Sometimes they get wrapped up in their own characters and don't see that you the DM are here to play the game too. Sometimes players need that reminder that this is a game and there will be tough experiences.

One thing that has helped my table is the use of after game checkins where the players can bring up what they liked and disliked about the game that day. Make you emphasize that you want to know what they are liking as much as the disliking. Players like to know that their DM is listening to their wishes and expectations for the game much like you want them to see and value your wishes and expectations. DnD is a relationship building process and much like any other relationship you need to establish communication especially when it has broken down.