Focus on your relationship with your boys. Your S14 is at a hard age. He is probably angry at the situation. Maybe you have trouble communicating with him. Sometimes, parents try so hard to protect their children's feelings that withhold too much, and the kids have to form an assumed explanation.....which is usually very inaccurate.
Make a real effort to include him when you do things with S13, as well as have one on one with him. If he thinks you and his brother is chummy, he might resent it or feel jealous. Man, I don't envy you! I would not want to raise teenagers again. Parents deserve a medal just surviving. .
Whatever happened in your childhood that still affects how you operate in adult relationships today, I hope you can receive help from your IC. It breaks my heart, Holding. I suppose we all carry something from childhood that negatively mold our adult years. If we can identify "it" and know how it is affecting our current life, then surely there is an answer in how to resolve, overcome, or deal with it. ((hugs))
Btw, discussing the co-parenting or visitation (whatever it was she was texting about) is not considered relationship talk. I say this in case you have appeared stubborn in communicating with her about the kids.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!