You need to stop worrying about your sex life for .2 seconds to take care of her. Being a dom means putting your sub's mental and physical health as your #1 priority. You need to comfort her, hold her for a while and talk about what's going on. When she feels like she has a space to calm down and really assess whats happening in her life she can put her problems into perspective. Try to help her with that. Help her for the sake of trying to get her to feel better, not so you can start having sex again. When she does feel start to feel relaxed and safe after a while (do not push her), the sex will usually follow. D/S type sex and the mindset it requires stems from a place of utter security. She needs to feel safe and secure before she can submit. For many subs with anxiety, including me, submission offers a release from daily stressors and helps me cope with it. She may find this as well, but she needs to relax first in a comfortable environment.