My advice is to think that, "My heavy negative karma, which has been created, can be purified."

All living beings can change their minds, have realizations, and achieve enlightenment by practicing the Dharma, and because of the clear light nature of the Buddha, which is the ultimate nature of the mind. It is temporally obscured by temporary obscurations, but our mind is pure by nature, so the obscurations can change, can be purified, the mind can change, and we can become Buddha, fully enlightened. For example, due to one cause and condition, the mind can be dark and foggy, but due to another cause and condition, it can be cleaned up completely so it becomes beautiful. Our mind can be totally clear, awakened, and enlightened by other causes and conditions, which make this possible.