For those saying that it will have originally been a fifteen year sentence, no it won’t. There is a threshold where half a sentence is served and beyond that there is a minimum sentence. If he served 7.5 years then the sentence is likely to have been around that level esp if he went back in after violating his parole.
That doesn’t mean fwiw that a 7.5 year sentence isn’t serious, it most definitely is, but it won’t have started out as a fifteen year sentence.
Also, the OP hasn’t said that he was a child abuser. There seems to be some implication, but given the OP doesn’t actually know I think it’s unfair to speculate at this point.
OP, a 7.5 year sentence is serious, so you need to find out first and foremost what his crime was and what the conditions of his parole were that he broke. Also whether there are any conditions set for his release i.e. if his sentence relates to a crime against children will he likely be barred from contact with them anyway. If so then this will be much easier to deal with in terms of his contact with your DD..
If not, then it’s more difficult as A, your DH is his brother and presumably closest surviving relative, and blood attachments can be complicated plus people do change and your DH may legitimately want a relationship with his brother - a relationship which has been lost for the past seven years. Also, as your DD’s father he may want his DD to have a relationship with him, and if his crime wasn’t against children or violent in nature then simply arguing that you want your dd to have nothing to do with him isn’t as straightforward.
But first and foremost you need to find out exactly what the crime was and go from there.