Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
Are there any children involved and what income do you each have?
Since she is not living there she is no longer responsible for any of the Utility Bills and can ask for them to be transferred into your name.
Legally she is still responsible for the rent so far as the landlord is concerned - but since you are living there and she is not you will find it difficult to force the issue
Please ask if you need further details
Since she is not living there then yes you will struggle to get any payment from her