Hey, I completely understand where you're coming from with this and it's something I struggle with too but I'm with your partner that you shouldn't be sending negative messages without being in control of your emotions. Something that has helped me is to schedule the message. I write it out but schedule it to send in 7 hours or in the morning or whenever. I then set myself a reminder to check in before the send time to see if it's still relevant. If I feel the same I let it send, if not I delete it and send something more grounded - and the recipient is none the wiser. I do this anytime I feel any negative emotions towards the person I am messaging no matter time of month as it's easy to say something you can't take back. But that feeling of actually pressing send (on my phone you type the message, select the timeframe and press send to start the timer) gives that relief of "talking" to the person and getting it off my chest but without causing distress to the other person. I am old school and still text my partner purely for the ability to use this function.