How Can I?

How can I call myself a Christian when I have this one person in my life that I can't stand? I just don't like anything that person does or says or values or is. Said person doesn't like me either. We try to stay away from each other as much as we can but we can't totally....we have a common bond....children. I have tried to like this person and to include him/her in family get togethers, for the sake of the family, but there is always some excuse why he/she is not able to attend. I know this person lies to me. I don't like lies, do you?
How can I love this person? (like the Bible says I should)
My rotten feelings were brought to a head again after I called to see if our grandson was coming over yesterday (a normal event for 8 years) and was told 'No'. End of conversation. (that is his punishment, if he doesn't behave he can't come over here- is that right?) His parents are separated right now. They may try counseling to work things out, but I have my doubts. I believe that in order for counseling to work you must WANT to change your ways. Both are very stubborn (and then they wonder why 2 of their 3 kids are???) I really can't see the 'thorn in my side' changing. The only reason I'd like the parents to work it out is for the children, the really deserve some stability in their lives.....they don't even know what it means, they move at least once a year. Our grandson told me he hates moving. From little on I could see that he thrived in a routine. Could that be part of the reason for his so called 'behaviour problems'???  That parent has him on meds rather than try to reason with/parent the child.
How can I get past all of my anger and hard feelings?
Right now they are staying at the other grandparents and we only see the one boy once a week (but not this week). They live 6 blocks away from us. Once in a while the older brother comes over, but never the younger one. He was kept away from us since he was a baby so I only see him in the car when our other grandson is dropped off or picked up.
I just don't know what to do. I cry because I love the boys and miss doing things with them. I can't even call them on the phone....the parent has a cell phone and doesn't answer me or is at work. So I have to 'suck it up' and try to be nice and pretend to be happy.......it worked when I was a waitress....so maybe it will work with the 'person' I would like to get along with but just can't stand.
I hate hating this person but I still do.
How can I do this?
How can I handle this sticky situation?

Thanks for reading (if you made it this far), I needed to vent.