No need to wait until he was caught alone with their mistresses. If you have a strong suspicion, asking him directly is the right way. Do not be afraid to express your suspicions once all the evidence you find.
2. Do not Delay.
Delaying longer to ask her, will make her feel on top of the wind. Remember, that the longer he was involved with the affair, it would be more difficult to remove.
3. The Right Time.
In order not to heat up the atmosphere, smart divide the time to discuss this with him. We recommend that when she and you are relaxed, not when he was tired. Try to talk calmly and without emotion.
4. Give time.
Try to give it time to respond and explain. If the explanation logical and believable, discuss ways of communicating that can be accepted by both you and your partner so that next time no more misunderstanding.
5. Request a Proof.
If you can not accept the explanation, ask for proof. If he refuses, the choice is yours: accept to be treated like that (at-emphasized) or end your relationship.
6. Follow Conscience.
Follow your heart and take the best decision. A healthy relationship should be mutual trust one another. Maybe you still love, but love without trust just going to make you and your partner hurt each other.