Did you have a solictor with you when you were interviewed? If not, or if they were just a duty solicitor, if you have the means to get one then get a criminal solicitor lined up and brought up to speed. Do not engage in any more interviews without a solicitor present no matter how nice or friendly anyone might seem.
I assume this is one of those "cry rape" cases because you fell out or argued AFTER the event and this is some kind of revenge (sometimes, who knows that they do it?)
Bear the following in mind:
You confirmed that you had sex, which is good.
They will then need to provide evidence to the contrary OR evidence that the claimant was legally unable to provide consent.
The burden of proof is still on them.
Go and see your GP. Tell them how you are feeling and WHY. Remember that the conversation is confidential but having it recorded that you were feeling so low is important. It makes a formal record of the effects on your mental health. That means that in the future if you have to claim how badly it effected you (mental health, PTSD) and someone doubts it, you can confirm you felt so bad you needed medical help. You have nothing at all to lose.
Who else knows about what has happened?
(I recommend you start your own topic too, so this one doesn't get lost).