A wrecked family unit - from anonymous

Dear Prison Widow UK. Please don't publish my real name. Thanks in advance.
My partner is in prison convicted of fraud. I had no idea she was committing fraud.
Anyway, this week she sent me a letter saying that we were over. She has fallen in love with another inmate of the same sex.
I am devastated. We have been in a relationship for 9 years and have a 6 year old little girl. I have cut my hours down at work so I can care for her whilst her Mum is in prison. It's not easy but I'm her Dad and she comes first. 
In the letter, she says that she does not want me to visit her and that her Mother will bring our daughter to see her. The family unit has been wrecked and I do not know what to do or who to turn to. I am in pieces. 

Information and a list of support groups have been forwarded to the sender.