Hello, this is Kitt and I suspect you are reacting to the situation and are feeling very hurt so the "Stinkin thinkin" thoughts have snuck up on you.
I do not know why your Father is acting this way but I agree with Shy, invite him over and find out what is going on. BE assertive, tell him when your were excluded from the wedding it made you feel very sad and depressed. Tell him only how you feel, don't start blaming him...........or it turns into agression and both parties get upset and nothing is accomplished.
You are a wonderful and special person, do not let how other peoples behavior or what they say dictate who you are. Only you can allow them to hurt you. Believe in yourself and if your thinking of up-rooting and leaving town do it for the right reasons and take your children with you.
They have done nothing and they would rather be with you then anyone, you are their Mother. Love is what they need, the love of a Mother.
You can do this, I know you can.
Gentle Hugs to you