1. past tense (already happend) 그러지 말았어야 했는데... 그곳에 갔어야 했는데... 2. present(future) tense 그러지 말아야 하는데... 그곳에 가야하는데 isn't it helpful that such a simple answer^^?

Hello, Jiwon. We use this to express lament or regret what already happened. 그러지 말았어야 하(or 했)는데! (I/you/someone) shouldn't have done that! (But I have done) 그 곳에 갔었어야 하(or 했)는데. I had to go there. (But I couldn't)