The Celebrity Big Brother star called off her engagement to Adam Cottrell last year after he was charged with assaulting her and criminal damage following a heated row.
Cottrell was later sentenced to 120 hours of unpaid work and placed on a 12-month community order with 12 months' supervision, after pleading guilty to the charges at East Hertfordshire Magistrates' Court.
However, Cassidy has now decided to take Cottrell back following an emotional phone call in which he apologised for his actions and asked for help battling his alcoholism.
"I know many people will question my decision. Others will disagree with my choice. But I do forgive Adam. We are back together and I strongly believe we can make it work. At the moment we are taking it one day at a time. It's the only way forward," Cassidy told The People.
"But we love each other to pieces and are happier than we have ever been. I don't want people to think of me as a victim. And I certainly don't want people to think I'm going back into a violent relationship because I am scared to be alone. I would never do that to myself or to my daughter.
"I now realise everything that happened between Adam and myself was down to alcohol. And he knows this too. But that is why he has sought help and is in recovery. He has not had a drink for more than 60 days and I am very proud of his achievement.
"I will never forget the things he did to me during that awful time but I do forgive him. He says he is deeply sorry and I believe he means it. Now he needs to forgive himself and leave what happened behind."
Cassidy, who has a 17-month-old daughter with Cottrell called Eliza, added that her friends and family are "very wary" about the reunion, but insisted she is "100 per cent happy" and "90 per cent certain things are going to work out".