This is good advice from Lama Zopa Rinpoche on giving up a guru who is a Dorje Shugden practitioner.
http://www.lamayeshe.com/index.php?sect=article&id=335It is obvious that it is not good to forsake one's guru unless the guru himself has released the student from the relationship. In which case, we should never give up our guru who has given us Dorje Shugden practice. It is really sad that people are being made to choose between whose samaya to keep. In this case, even though Lama Zopa had received Dorje Shugden practice from HH Trijang Rinpoche, Lama Zopa decided to keep his samaya with HH Dalai Lama instead, outwardly at least. I do believe from the advice Lama Zopa has given on Dorje Shugden that he is privately keeping his practice though. Who knows, maybe the Dalai Lama is too!
Forsaking a Guru(Advice given 4 April 1998)
A student wrote to Rinpoche saying that he had forsaken one of his gurus, Geshe Kelsang Gyatso*. The student said that he was not keeping his vows and was aware of the negative karma that could result from these actions. Rinpoche answered as follows.
Once you have made a Dharma connection with the virtuous friend, your guru, you cannot give up this relationship unless the guru himself or herself says, “Don’t come,” or “Don’t regard me as your guru.”
By giving up Geshe Kelsang Gyatso, you have created heavy negative karma in this life. Since you haven’t given me up, I suggest that you confess to Geshe Kelsang Gyatso about what happened, and devote yourself again to this virtuous friend.
According to guru devotion practice, no matter how many gurus you have, you should look at all of them as one being, one mind, and that is Dharmakaya. That view must come from the disciple’s side. You look at them as one mind in different bodies, acting in different ways, according to the karma of sentient beings and their ordinary mistaken minds.
This is what one should practice, if one wants profit and not loss. So, change your attitude and apologize to Geshe Kelsang Gyatso. Confess to him and follow him again, unless he says, “No”. This will help lighten your heaviest negative karma.
In this world, people are so afraid of getting cancer or AIDS, but they don’t think about eons of suffering in the hell realms. There is such great suffering in the lower realms that cancer and AIDS or whatever suffering one can encounter in the human realm seems a great comfort and pleasure by comparison.
Causing heresy and anger and giving up the virtuous friend is much worse than killing and waging wars. This is because the object is very powerful. One’s guru is the most powerful among all powerful objects, such as buddhas.
The karma from forsaking one’s guru is worse than the karma generated by Hitler and Mao Tse Tung. Mao Tse Tung caused harm to many holy beings, but they were not his gurus. In the world, someone who kills many millions of people can still achieve enlightenment in that same lifetime. But generating heresy toward the virtuous friend and giving up one’s devotion to the virtuous friend makes it difficult to achieve enlightenment, even if one practices tantra with much hardship. It will be like taking a rebirth in hell.
Therefore, what I am saying is this: In the world, actions such as killing and waging war have very bad repercussions and are terrible, but the karma from these actions is mild compared to heresy and giving up one’s guru.
You can see in the outline in the lam-rim, even if one commits the five heinous crimes—killing one’s father, killing one’s mother, drawing blood from a Buddha, causing schism in the Sangha, and killing an Arhant—one can still achieve enlightenment, but not based on mistaken devotion to the virtuous friend. If you read Liberation in the Palm of Your Hand, or Essential Nectar, particularly the lam-rim outline on guru devotion, you will understand.
I advise you to make your negative karma smaller by apologizing with regret. Practicing Buddhism is basically your choice. If you want to be free from suffering and its causes, delusion and karma, this is what you need to do: practice the Buddhist path and the Four Noble Truths. If you don’t want to be free from suffering and its causes, then there is no need to practice Buddhism. If you don’t want happiness, then don’t practice virtue.
*Geshe Kelsang Gyatso, a teacher in the UK, who continues to engage in and encourage the Dorje Shugden Protector practice.