He tries to keep her away from me and doesn't want her talking to me

And how do you know this? Your GF telling you? That's playing games trying to get you and the ex to tangle horns. She's the one you deal with, not her ex. Unless you are a fly on the wall you have no idea what is true anyway. Tell her how you feel about her (she may feel that you don't express love enough and this is her solution) but that you aren't going to get dragged into the boxing ring with her ex. (I know, I'm mixing metaphors.)

And how do you know this? Your GF telling you? That's playing games trying to get you and the ex to tangle horns. She's the one you deal with, not her ex. Unless you are a fly on the wall you have no idea what is true anyway. Tell her how you feel about her (she may feel that you don't express love enough and this is her solution) but that you aren't going to get dragged into the boxing ring with her ex. (I know, I'm mixing metaphors.)

Well I spend every Sunday with her and she is all lovey dovey with me but her ex gets mad because she wants to be with me but he won't leave her alone about it and she doesn't want to be a ''itch'' to him but I don't know what to do I love her

I just don't no what to do I love her honestly but its hard

How many ways to say it?
She's playing you against each other.
Do you think we are that far from the animals who fight to the death over the female, while she stands there waiting?
Do you think the ex is doing what he's doing independent of what she's encouraging him to do?
He won't 'leave her alone' because she LETS HIM and maybe even teases him into doing it.
Tell her you aren't interested in the fight and that she has to decide, and if she picks him, grin and bear it, but if she picks you, stand your ground in the future if it happens again.
Is spending time with her worth the pain? She probably wants to know if you are strong enough to tell her she has to decide.
Sometimes just the act of being strong and decisive is enough to drag you out of a whimpering onesided puppy dog love based on fear of losing the other person.