Your husband has occupancy rights in the house. These exist for two years after he leaves. If he comes back within two years he has a right to remain. You have to ensure that he doesn't come back within the two year period, either by trying to continue negotiations or by settling the financial side of things. You can't prevent him moving back in by selling or by transferring to your current partner any share of the property. My advice is that you have to get a settlement or gamble that he won't move in before the expiry of the two year period. So to be fair to your solicitor there are limited solutions to this. The issue relates to the Matrimonial Homes (Family Protection) (Scotland) Act 1981 which you can read online. I hope that helps. Please leave a positive rating so that I am credited for my time.
You can't change the title as you would, as part of that transaction, have to sign a document saying you have no entitled spouse under the legislation. You can't do that as if you did it would be fraud. The two years is calculated to the exact date he left so you either have to try to delay this until after that date or reach a settlement. Those are your options, I'm afraid.