My most dear, most kind, most precious wish-fulfilling one,
Thank you very much for your kind letter. I am not qualified, but I will try what I can and you try whatever you can.
It is most excellent what you are thinking, the way you are thinking about being in prison, using the time to practice Dharma, to actualize the path to enlightenment for yourself and to free all sentient beings from the oceans of samsaric suffering. Also to purify the negative karma that has been collected from beginningless time that causes rebirth in the lower realms. So to use the time in prison to be free from this forever and to achieve enlightenment. That means you are in prison for all sentient beings. That is the best.
In reality if you were out of prison, you probably would not practice Dharma. We are usually totally distracted in samsara, in pleasure, having no interest in practicing Dharma, being lazy. So in this way being in prison you can understand really how to practice, to actualize the path and to achieve enlightenment for all sentient beings, to free them from the oceans of samsaric sufferings and especially to achieve enlightenment for sentient beings.
Please make your life most meaningful with the thought of bodhicitta day and night, and in every action that you do.
With much love and prayers...