Want to try and get debt free but don’t know where to start

Hello,

I have recently spilt up with my husband and have been left with what feels like horrendous debts, totalling about £13k on 3 separate account. All have defaulted as I did not have the money to pay them and he isn’t for giving me any of the money that he spent on them. Typically everything was in my name so he doesn’t care. The biggest is a Barclaycard which has £7k, there is a next store card for £4K and an mbna card at £2.5k. The last year I have worked hard at getting myself back on track with getting somewhere to live for myself and my two children and I want to try and pay these debts off as it is affecting my mental health constantly worrying about them. Is the best way to just contact these debt agency’s and agree a payment plan? It feels like I will be forever paying them off when a lot of the balance occurred from interest when I didn’t have the money to pay. On hindsight I wish I had of contacted them sooner but I was in a bad place after the split and buried my head in the sand. Looking for some help and guidance please.