This is not cool - I am sorry. Investor here - they should never do that. Make sure you tell others about how this went down. If they were planning on getting rid of you, that needs to be part of the upfront discussion etc.
But founders should talk to other founders about their experience with different investors. The good, the bad and the ugly.
In those situations, you can make it clear - in objective terms - what happened and why you would not take money from them again. Don't call them names or anything.