Can’t ever fold here once you raise, but as Andrew says, the raise isn’t a necessity.

Don’t use questions or phrases like “was that a donk call?” – they don’t mean anything. What’s the definition of a ‘donk call’? How unprofitable does something have to be before it qualifies? It’s an emotionally-charged phrase that ends up being a way to berate yourself and add emotional significance to the situation, making it harder for yourself to actually figure out the answer. As soon as you frame it as either “donk call” or “not a donk call”, your brain is going to look for reasons not to think you made a donk call, so it’s going to obscure the actual answer.

Let’s say you flat his bet…why would he shove a brick turn? He’d probably have around 3x the pot left in his stack. He’s much more likely to just bet a normal sizing, leaving you a much easier decision. You’re fixating on an unlikely scenario that is once again obscuring the actual decision at hand – by all means, plan for the turn, but if you think it’s that likely that he’ll shove a brick turn, then don’t let it paralyze you, just make a plan for what you’re going to do, and follow through with it.

Finally, if your instincts told you he had 87 exactly, you need to work on your instincts. Your instincts should be putting your opponent on a range of hands, not one individual hand. Here, you’re solidly ahead of the villain’s range, and I imagine you’d still be in very good shape on most turn cards too. Focus on evaluating your opponent’s range.

You didn’t really make a significant strategic mistake in this hand – instead, your biggest mistakes were mental game ones. Your thinking is clouded by a variety of judgments and emotions that make it harder for you to make the right decision in the moment. I’d recommend getting yourself a copy of Jared Tendler’s books, The Mental Game of Poker 1 + 2, and fixing your mental game flaws before you commit to the belief that there are flaws in your strategic approach. There may be flaws in both, but do your homework first. 🙂