I don’t think that is a Bullmastiff. I think it’s an English Mastiff. Bulls have bulldog-like faces and are not as tall as English. They are known to be more aggressive than English Mastiffs. I had to put down my ENGLISH Mastiff 3 weeks ago. He was 4 and a half, and had always been a challenge. I’m not exaggerating when I say he weighed 200 pounds... he did. I have no idea how “tall” he was because we wouldn’t let him jump on us. He was the most wonderful dog (in spite of the drool on the floor, walls, and ceiling) with my husband, grown kids, and their dogs, and he also was friends with a St. Bernard. In spite of that, he would go ballistic at *some* people. We worked with him for over 4 years, and couldn’t get that part out of him, so we decided we couldn’t wait for the inevitable to happen, we had to put him down before he attacked someone. It was very sad, to say the least, but we aren’t living in fear anymore. There are people who refuse to put their dog down UNTIL he bites someone, but that is way too late IMHO. TYPICALLY, English Mastiffs are “Gentle Giants”. Sadly, we got an exception to that.
Very sorry to hear about your sad experience. One reason I can think of to research a breeder very carefully is that people have been working with Old English Mastiffs to get a bit more health into the breed, which has been in decline. As a result, sometimes the inbred kindly temperament has suffered.