Hi Marti, welcome to HW. I hope you like it here.
Firstly, it makes complete sense to me that you get a thought in your head that takes over. Happens to me all the time! Nothing abnormal there, especially considering your current stress. But it is something you can work on and get better at over time. I'm a big fan of CBT counselling (you can access it online..moodgym) and positive thinking.
A diet free of caffiene, preservatives and fatty foods has helped me more than I can believe (although I do sneak in chocolate!!)..and I try to jog a few miles every day to get rid of the excess adrenaline..
Marti, you are NOT odd, trust me! You have a huge stress in your life, take it one day at a time, take care of diet and exercise and if things gets worse, please consult a doctor. You are not alone in this. Keep us posted.
Meg