The "tie" can last anywhere from 5 minutes to over a half hour. DO NOT try to seperate them, they WILL come apart on their own. Keep both of them calm until the do so. At this point, you need to consider her pregnant. You can likely expect pups in 58-63 days. If you don't want her to have pups, you can call your vet and have her spade..taking care of this litter and preventing any future litters. Good luck and again, let them come apart on their own and keep them calm until that happens. :)
How many days into the heat cycle is your female dog?
Is she stressing out at this point?
I see you went offline and want to make sure everything is ok.