Pack, great news on the project. One of the things that turned my emotions around in my sitch was knocking it out of the park at work! Keep up the good work.
On the Munich house, let it go. Emotional detachment includes "things" that you are still putting emotional value on. There is no reason to hang on to a house that is keeping you attached for sentimental reasons. Get rid of it and go get that sports car!
As far as missing birthdays, you don't have to miss them. You just have to celebrate them later (or sooner). People put so much artificial emphasis on the DAY. Is the DAY more important than celebrating with your child? Of course not. So when you have him, celebrate the birthday with him! Use this same perspective with holidays. The holiday doesn't have to be celebrated on the day, it can be celebrated whenever is convenient. I see so many D'd people struggle with this needlessly.
Yes, you should not have put your S7 in the middle of that. He clearly felt he had to tell you both yes. SO learn and grow from this, do not beat yourself up. You made a mistake. They happen. Mistakes are not the problem. Not learning from them is. So learn and grow from that mistake.
As far as whether or not you should give her the extra 1 or 2 days, that is entirely up to you. I will never fault someone for wanting to spend more time with their kids. So if that 1 or 2 days is important to you then you tell her that her illness was unfortunate but that you have plans for the kids for all 18 days and you will not be willing to give up any of that time. Don't let her have them to be "nice" but don't not let her to be vengeful. Remember, emotionally detached. Make the decision based on what YOU want.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018