Why to fight?
Step1: You have been associated with this karma because of your past actions. Do this karma as per your Dharma, with this you wont pile up pending karmas. This is sequential one by one elimination of Karmas. — Yoga or Karma Yoga.
How to be stable after fighting near and dear ones?
Step2: In order not to have pride or guilt associated with the karma, forget it as soon as it is done and hop on to next. Be dissassociated like drop of water on lotus leaf. If you cant do it yourself, say the mantra “Krishnarpanamastu”. This will also relieve one from pain and joy resulting in the phala of the karma. Karmaphala always is a liability. Krishnarpanamastu avoids this karmaphala and hence path to Moksha is cleared. — Karma Tyaga.
(This is KarmaYoga associated with Bhakthi and hence Bhakthi Yoga, Bhakthi Yoga is not independent of Karma. However Bhakthi eliminates pride and guilt, and without that a person would rmain humble and down to earth. Also this is renunciation of karma and karmaphala after executing it. Krishna never asks to relinquish karma without doing it, Ma Te Sangestu Akarmani)
Would I be doing a great mistake or great benefit by fighting? what will be the consequence?
Step3: Realise the way in which God creates things – Prakriti Purusha. Realise the complexity of universe, inverted ashvathha tree, eternal souls etc. You can also see my Vishwaroopa to know how complex the universe is. The karma that has been attached to you is result of past actions, execute it without worrying. In any case it is so insignificant and will be done anyway. — Karma Yoga with Gnyana
(Yoga means karma yoga only, Gnyana is an attribute for quicker realization. This is not independent and hence karma should never be avoided.)
I understood Karmayoga, Karmatyaga and associated Gnyana. I will do it. How to realise God within me? What is the nature of God?How to be in union with God?
Step4: God is there everywhere in all beings. He is reflected more in the best unit of the class. He is hence the vibhoothi. Realise that and be the best among humans. You will be one with the God. — Raja Yoga
(Being one with God is the ultimate Yoga. Krishna is the final God of Yoga and hence Yogehwara. Patanjali’s Yogashastra is an attempt to realize God within you in 8 different ways.)
Step5: Understand all this and finally do as you please. Life is a state machine. Wherever there is Krishna, the one who gives answers and the mortal who shoots questions victory will always be there to humanity.