First talk to your partner and explain the situation. If you're a victim, explain to your partner that you no longer intend to tolerate their situation and prefer to leave. If you are unable to choose between two loved ones, talk with each of them and try to decide with whom you want to stay.
If you can not decide on a breakup of a relationship, try to look at the situation from the outside. You should clearly understand in what position you were and what it may bring. If you can't choose between the two partners, then torturing them and yourself. If you were one of the victims, think, is there something good in such a humiliating position?
Don't threaten, don't cry and roll scandals, trying to get his. At the same time ignore the provocations of the partner and his attempts to force you to abandon the decision. You should not believe and sweet promises. Married men rarely leave the family, as a married woman, if a partner has found love on the side once, there is no guarantee that it will not happen again. If you are sure that doing the right thing, do not delay the breakup of a love triangle.
Go confidently but wisely. For example, if you plan to leave wife or husband, discuss in advance the division of property. If you have children, it is important to decide how the rest of their life after divorce. Do not rush into the maelstrom with his head, not pre-weighing the pros and cons.
Learn to cope with their pain. As a rule, all the members of the love triangle are in an unenviable position. It does not matter, leave you or leave a bad taste still remain. Immediately refrain from such destructive ways to numb the pain, like alcohol, drugs, etc. Just try to start a new life, and if it gets too hard, ask for help to a shrink.