I originally post here as I didn't know where to put this

Friday night 2 women (around 18-25) jumped me while i was leaving a party, I was pulling scarf+gloves out of my bag and they start beating me around the head out of the blue.

I push them both off me, one realises I'm not who they are looking for and drags her friend away while shes screaming at me that I'm fucking dead. She breaks away from her friend, I shout "you swing at me again and you're getting hit" so she sprints up the road at me, jumps to hit me with both hands and I hit her in the face. (Note that she was in the middle of a running jump at me.) Big black eye in seconds and a bleeding lip.

They are both very very drunk. I wait with them while the police are called, I am arrested, was not put in cuffs, explained everything to the arresting officers, had to spend a night in a cell. I find out during the interview that the one I hit was 3 months pregnant..... Officers said that they are confident I am not going to get prosecuted.

I honestly feel fucking awful that this happened, literally the first fight I've been in since I was 10. However I do not regret defending myself.

I raised counter charges during the interview. I'm from Northern Ireland and am scared of retaliation attacks should I pursue this further.

She has two small children already, someone suggested raising a complaint to my local health trust. I do not know if I want to do this due to possible recourse against me.

Edit: Thanks for your help guys, it's very late here, I'll keep looking for your advice as it has been helpful.