Hi Liam!
How long is it since you adopted the boy? It’s important to pre-bond before you introduce, so spend a month introducing them to the IDEA and scents of another bunny by swapping their litter trays, toys and eventually entire hutches. You can also give each one a teddy and swap those. You should also give your new boy a couple of weeks to settle in before you start even pre-bonding.
The fight must have been scary, but it doesn’t sound like it was too severe. Fur often flies and looks worse than it is, but as long as no skin was broken, they shouldn’t hold too much of a grudge. I assume you have checked them both thoroughly for wounds?
After a month of prebonding, start introducing for short periods in neutral space (eg. 5 minutes in the bathtub) and be ready to intervene before they start fighting. It’s good to be wearing thick leather gloves/oven mitts so you don’t get bitten. Once they can do 5 minutes with no signs of aggression, increase the time.