Is there a way we can learn how to “handle” them? They do have a good side also, the side making us believe they are what we want. 

The good side you described, “making us believe they are what we want” is manipulation. That’s not good at all, and this is what can really destroy someone who falls for the smoke and mirrors. They hold onto that illusion so tightly and believe they are a good person and can or will change back at one point, meanwhile they are enduring abuse and losing themselves more and more each day.

There are reasons people do stay in relationships with narcissists. While I’m not saying you should, I also realize it can be more complicated than just walking away and some are not simply ready to walk away. 

I believe you have to radically accept who they are, not what they say they are, not who you want them to be, or what others think they are. This can be extremely hard because people tend to hold onto what they “want” to believe.

You have to manage your expectations. If you are dealing with someone with destructive narcissism, addictions, or a disorder, then you can’t expect them to act like someone who is not dealing with those things. Expect what they have already given you to always be the case. Don’t fool yourself.

Accept they view the world, relationships, and love very differently than you do. Many of us just won’t accept someone could be so cold, but the evidence is right in front of us every day. They can, and they are.

Don’t allow yourself to be vulnerable. This will most likely be used against you.

Limit your engagement to the most positive interactions possible.

Understand, that staying with a narcissist means your basic relationship needs will most likely not be met.

I think you should also consider what you are giving up by staying in a relationship with a narcissist. Learn from others who are speaking up about long-term relationships with narcissists. You will hear things like “I wish I would have left earlier” “If I could imagine my life like this, I would have left sooner, but I was so brainwashed.” “RUN” “Prepare to leave and do it”

I don’t believe we are choosing to love ourselves when we are in intimate relationships with narcissists. We are deficient in love because perhaps we never learned what true love is and many of us are blind to this because it’s normal, comfortable, and familiar. 

I would also say one of the best things you can do for yourself continues to learn how to take care of yourself and work on healing. I believe you will reach a point in your healing where you will shift your view of the relationship and be able to make a better choice for yourself.