One thing that helps me is to think of how other people generally react in similar situations and to make sure you got the full story before passing judgement. The other point to keep in mind is, is the relationship with the person abusive. In cases of abuse, it's not uncommon for abuse victims to feel like they're overreacting to everything so if this happens to you a lot with a specific person it might not be a bad idea to go through a checklist of symptoms you are in an abusive relationship (with a friend, parent or significant other). If it's a totally one off thing or you feel like you might over react a lot, proceed on to the other questions. Not that this only happens to people with mental illnesses, but I can only speak for myself. So when my mental illness was untreated I overreacted to just about everything. So for instance, my best friend used my expensive shampoo without asking. I felt really hurt by this because I am very particular about people touching my things, and my best friend knows this. Therefore I felt betrayed, basically, and all my emotions are dialed up to 11 because of my mood swings (thanks borderline). So my immediate reaction was to stop talking to her for the rest of the day. So it's really obvious to me now that this was an over reaction, but if you take it piece by piece: 1.) Do most people react to someone borrowing their things without asking by refusing to speak to them for an entire day? The answer would be no, unless you are including small children and I was in high school at the time -- in fact the fact that I can only think of small children doing this is a big red flag that this is an overreaction. 2.) Did I get the full story? No. Because I over reacted almost immediately after she confirmed that she had used it, I wasn't able to have a calm conversation with her about WHY she had used it. I just assumed that she had thought it was okay to borrow my things without asking and that she either didn't care that I would mind or didn't know me as well as I thought she did. In fact, I'm pretty sure I ignored her because I felt like she was ignoring me in a sense in that someone I felt so close to didn't know something that simple about me (like it came up a lot with other people and she was around to hear it so it felt like she was hardcore not paying attention to my feelings). In reality, after the fight cleared up I found out that she had used my shampoo only because hers was out, and didn't mention it because she figured I wouldn't notice such a small amount and that she was worried I would be mad at her for using it, which she was obviously not wrong about, but it also meant that the entire thing I was truly upset about, the idea that my best friend didn't know me all that well, was completely null and void, so it boiled back down to just someone using something without asking, and as I said, I over reacted. I also know that the person is not abusive based on the check list. In an abusive situation, it's common for people to seem to overreact to something small, when in reality there's another cause of them being upset. Like say your boyfriend forgets your anniversary one time and you start shouting at him, BUT your boyfriend also frequently puts you down by calling you ugly names or belittles you, then it might makes sense why you would over react to something small, because you already have a lot of negative feelings towards the person built up that you haven't expressed. TLDR; I would suggest writing down how you feel/felt and what kind of thoughts you had to explore why you felt that way as well as answering the questions of "do most people react this way?", "did I get the full story?", and "is this person abusive?"