Going through something similar with a pseudo ex-cofounder. He has been behaving extraordinarily passive aggressive.

For a long time, he hasn't been picking up phone calls, responding to emails, or completing tasks that he agreed to do. Sometimes he'll send a text, like seven days later, asking for a clarification on a requested-task that has now already been completed.

Things are finally starting to pick up. I don't know what to do. Technically he owns 50% of the "venture" but it's not like we've issued stock, etc. Things are hairy.