What to do when overwhelmed with Doubt - Practical Advice
There are times when there's nothing to do but watch. Put aside the expectations for yourself gained by reading the Dhamma. Unwise attention, in this case, would include reading about arahants and then judging yourself for not being like them. 

Just focus on what is right here.  Focus on the doubt itself, or on the body, and the feelings in the body created by the negative emotions - the constricted breath, the aches and tensions, the agitation, the rushing thoughts. 

Resolve to sit, but don't expect anything from the sitting- just put in the time. If chanting feels like a chore, just sit instead.

Find some small, easy, thing to do that is useful, or is kind and helpful to someone else, and do that. 

Or just sit still and count to 100, if that's all you can manage. These are all wise and skillful actions and are Dhamma.

If you just do your best to not nourish the already-arisen thoughts, then you are practicing Dhamma. You're experiencing an emotional flood, created by long-past circumstances. The flood is pulling away your energy and faith. Wise attention, in this case, is to let the flood wash through, watch your energy and faith fade away, and stay aware. Later, the energy and faith will return - it is inevitable- and you will have have strength again to nourish new, increased faith and energy, but for now, just do what you can.