Here are a few things to keep in mind when dealing with negative people.
1. Where's it coming from?
Do you understand why your son and his wife are so negative? Is it because they hate their job, feel frustrated, feel trapped in their life or do they lack in self esteem so the only way they can feel powerful is by hurting others? If you can understand where it's coming from, it's much easier to deal with. Some people seem to think that the only way they can get what they want is to be manipulative. Remember the saying, "the squeaky wheel gets the oil." They believe this and think that if they don't whine and complain that they won't be heard and that this is the only way to get what they want.
Remember that the negative behavior is a reflection of them. It tells you what kind of person they are and what issues they may be dealing with. It's not a reflection of who you are.
2. Just smile and remain completely detached
Whenever the negative tirade starts just smile and don't say anything. Remain completely detached from it and don't get involved in it. Leave the room if you can. The negative person is simply seeking to get a reaction from you. That's what they feed on. Don't let them catch you in their web of negativity because as soon as you do, that's when they start draining your energy.
It's the emotions that these negative people stir up in you that you need to learn to distance yourself from. Try just observing the whole scene. Say to yourself, "what a shame this person is so unhappy. Maybe some of my positive energy will rub off on him." This isn't always an easy thing to do but definitely a powerful technique. In order to get the full benefit from it, you need to make sure that you're aware of what's going on around you. It's easy to slip into auto-pilot and not realize until later how drained you feel. You need to detach yourself from the event while it's happening and just observe it.
3. Say, "Now tell me something positive."
Right after they've finished telling you some tragic story, say to them, "now tell me a positive story". Some people have no idea how negative they've become. That's what they're surrounded by day in and day out so it's just become a way of life for them. By being given the reminder, they may actually realize that being negative isn't the kind of person they want to be and may start to work on becoming more positive. Or, they may decide it's not worth telling you their horror stories because you'll ask them to think of something positive.
4. Imagine a bright white light surrounding you
Yes, this sounds silly but if you can do it, it's amazing how much of a difference it can make. You'll feel that their negativity can't touch you because you now have a force field protecting you.
5. What does it say about you?
Negative people want to get a reaction out of you. And the only way they can is if they hit on one your "buttons" or something that causes intense feelings for you. For example they may bring out past feelings of guilt or anger or make you feel like you're being rejected or that you're not good enough.
So, if there's one particular person who drains you the most, ask yourself why is it affecting you so much? Sometimes, you can learn a lot about yourself by analyzing what feelings it's bringing up within you. Once you figure it out and deal with it then you'll find that the energy draining person simply has no power over you anymore.
6. Try saying, "I love you, thank you, I'm sorry" over and over
This is kind of an "off the wall" kind of theory but it's worth a try.
7. It's not your fault
You may be feeling that you have to solve the problems of the person giving you this negative energy. You're not responsible for his life nor his negativity. You don't have to feel guilty for them being unhappy. Let go of trying to fix or help them. That's not what they want anyway. They want your energy and so you have to be strong and not give in to them.
8. Be enthusiastic and focus
If you can be a bigger person than they are then your energy will most likely start to rub off on those around you instead of the other way around. Also, the less you pay attention to them, the less they'll affect you.