Hi, I'd say you've got a right to be a bit bitter, it can just be human nature in a situation like that.
But the thing is you've really got what it takes to move on from that/and you will so just allow yourself to feel how you feel right now, you've been through a lot and I know you have it in you to come out stronger (and not bitter!) as you gradually put it behind you.
And don't blame yourself for having been affected, you've had a lot of history with them, a lot of "water under the bridge", what matters is that you're on the right tracks now. Might still be some residual feelings coming up from time to time, but you are now seeing "the bigger picture" and that's got to help.
Best wishes
Alison