I feel for your situation and your tragic losses. Over two years i have come to accept that sometimes it will be tough, and that the awareness and acceptance of that is enough to help. I have learnt enough not to make it worse by struggling and fighting. Soetimes these periods have obvious precipitants, sometimes they don't. All things pass, it can be beyond our control.
I have found reading some self help books on mindfulness helpful. I have learned there ae other things i can focus on other than my problems and ideas churning through my mind. With practice it helps.