You can't change the past. You can't predict the future. All you have is today. Try to stay focused on how you feel today. When you feel yourself getting anxious about something in the past do something that distracts your thinking. When I need to get my mind off things that are bothering me I go talk to my horse and pet him. Do you have any animals? Even a stuffed animal will work to pet and focus on the softness. If you are artistic you can paint or draw or whatever makes you feel good.