Agreed As Viper93 already said, there was no foul. Your moves were legitimate
This is down to the individual. If someone wishes to aggressively defend, they may do so. Once the opponent has attained overlap, the driver in front has missed his opportunity to block the way, but if he hasn't already made a defensive move to prevent someone overtaking, he's within his rights to get in their way and force the guy behind to ease off.
Races are not just won by the fastest guy on the track. Sometimes they're also won by the "widest car" on the track. Some of the most entertaining racing I've seen on the CTRA has been from drivers who have an extraordinary ability to place their car exactly on the track where the guy behind wants to be. This is a skill that is no less to be celebrated in racing, IMO.