It's completely up to you. You need to consider your wants, needs and values. There's also another option besides a DNR that you can get. It's called Advanced Directives, and allows you to say interventions you want and don't want, it has more flexibility than a DNR. For example a DNR means the doctors wont put a breathing tube in, wont do chest compressions, wont provide oxygen, and wont use drugs that could bring your heart back AFTER it stops beating. Advanced Directives allow you to list if you want drug interventions that could correct a fatal heart rhythm, or if you don't want chest compressions. Again, it's up to you, you need to decide what's best for you (whether you don't want any interventions, or whether you want some interventions) while considering your values. Regardless of whether you decide for a DNR or an Advanced Directive, you'll want to have discussions with your spouse and both your children.
Personally, I would choose an Advanced Directive because it gives you the flexibility to say yes or no to interventions, whereas a DNR is an absolute no unless you change it.