I need pretty urgent relationship advice, about my girlfriend's father and family. Can anyone help?

Okay everyone, here's my problem. I'm 16, and I've been in a relationship for most of this year. My girlfriend is 18, and we are both very close. I'll establish upfront that I'm only here to help her, and make her feel happy and safe in everything. She's had some mental health problems in the past, and she pulled herself out of them.
However, both her folks had alcohol problems in the past, and although her dad has managed to stop drinking her mum still has a problem. My girlfriend (I'll call her Ashley) has been working on helping her for a while, but her dad often berates her mum about it which doesn't help. Her dad is quite religious, which meant I should have been a little more respectful I think, but Ashley and I decided that she is an adult now, and she can decide what she wants to do. Her parents like/d me, her mum is very fond of me and I had a great relationship with both. Her mum is less restrictive than her dad, and is fine with us having sex.
Here's where it gets messy
So, we have had sex a few times, and I ended up with one helluva hickey (she had one too, but smaller and matching) which seems to have slightly put off her parents. Neither hickey was given during sex however, actually just cuddling at her place. Anyway, her parents have found out about us having sex and now her dad seems to be angry. I was at her place, and he texted her mum saying to make sure I wasn't around when he got home. When she tried to ask him about it later, he avoided her and told her she had made poor decisions. We (Ashley and I) have talked and are considering seeking counselling about everything. I am usually very stable and calm, but this whole thing, after going so well, is turning to shit and I want to save it. Her mum is also going through a tough time and Ashley herself is starting to struggle and I feel I'm trying to juggle and carry the weight of supporting her and helping her family.
What should I do?
I need pretty urgent relationship advice, about my girlfriend's father and family. Can anyone help?
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