Universal credit overpayment accidently

) I am feeling really anxious. I started subletting my property on for 6 months. This was after a very hard court case (family court). I was in a lot of debt to my family and I didn't feel safe in my home because of my ex partner. So I let my property out and lived with my partner for 6 months, I didn't change my circumstances and claim the subtentants lived at mine as I saw the income doesn't count (I have now looked into it further and realised I still needed to declare they live there). I also didn't declare I lived with my partner, it wasn't a fixed term thing as I was only ever going to let my property out for 6 months before moving back after all the court stuff died down. I didn't declare any of it as I wasn't aware I needed to and I was having an extremely hard time.

I have told universal credit about my mistake which started in October and happened until April. I think I've over claimed about 9k. It was a genuine mistake and I feel awful! I have 2 young children and I am so worried I'll end up in a lot of trouble and lose them, as ive been told this could be seen as benefit fraud. What could happen to me? I'm hoping just to pay it back as I will get a loan out if I need to, but is it likely I'll be prosecuted? I wasn't reported, I have admitted it myself when I realised the mistake I'd made.

My daughter has had a very traumatic upbringing and is very reliant on me