Where are my boundaries?

I am currently working on the topic of boundaries. I’m struggling with setting boundaries because in the moment I don’t feel that a boundary has been crossed, so I don’t feel resentment. Only after the event I realize that there has been a boundary violation and that I should have felt resentment – sometimes I feel the resentment after the event, but not always. This makes it very hard if not impossible to follow through on the consequences I stipulate for the boundary violation.

Example 1: Yesterday my parents showed up at my house unannounced to visit. I let them in. When they came in they started to tell me about their current problems (a water pipe broken at their house caused considerable damage, legal fights with a tenant, etc.).

I felt sorry for them, so I did not say anything with regards to their showing up unannounced. Also, I rent a house that my parents own. Later, after they were gone, I realized that their showing up unannounced was in fact a boundary violation that I should have brought up with them, however, I still did not feel resentment but continued to feel sorry for them.

Example 2: When my husband talks to me in a way that is condescending I am too shocked in the moment to recognize this as a boundary violation. Only several moments or even hours later I realize that I was treated disrespectfully and then I feel resentment.

So, is this me confusing something with a boundary violation that in fact was not a boundary violation? Or is this an issue of not loving/valuing myself enough in order to set proper boundaries and if so, how can I work on this?

Thank you