Ignoring me?

Sad to say the old adage is true:  blood is thicker than water.   That fact, plus what ever "story" he told them about you is all the justification in their minds that you were in the wrong somehow.

Don't expect an ex's family to maintain contact with you.  Even families that got along very well, know the truth about breakups, etc:  they still drift away from the former spouse after seperation/divorce/death.   For some, it is just "to awkward" to maintain contact.

Let them go.  Let go of the pain and hate your Ex caused you.  Any negative feelings you hold onto will only hurt you in the long run.  Not saying you must forgive your Ex - but find a way to not let the hurt and anger, tho justified, eat away your happiness.   Hate only corrodes the vessel that contains it so they say.

Hope this helps you.  May you find the pease of mind and heart you deserve and seek.

It's quite normal for siblings and family of an EX to distance themselves from their relative's EX.  

You need to grow up and toughen up. I expect he has fed them all sorts of lies about you. Being siblings they prefer to listen to him. Just move on. They have lost a good friend in you and you mustn't be affected by it. If you allow it to affect you he will have won. Sounds like the whole family are sh!t anyway.

To send them cards is well meaning, but if they don't see the problem with their son cheating on you, and have chosen to ignore you completely then you should probably distance yourself from them and move on.

Edit: Got it, I read that wrong. If his family condoned his behavior, all of them probably hold something against you.

It's kind of you to send a card to his sisters, but I don't think you can maintain a friendly relationship with them. Regardless of how wrong their brother acted, his sisters will take his side and hold something against you, so just forget about them.

1. Why did you assume they would take your side over their brother's? He may have done wrong, but he's family.
2. Are you really more "heartbroken" at their diss than the fact you were cheated on?

It is better to not communicate with his family. Let it go. Move on with your life. Good Luck. I want you to be happy.😃 

When you break up, most people let the entire family go. so let it go.

Dont compromise, be patient, if he realize that better if not forget him

https://www.youtube.com/watch?v=tXIJQpYF51c&t=121s