Just adding to what others have said - totally understandable it should feel so difficult to talk about, we all carry so many complex feelings and shame around stammering. Do you stutter most around parents because you can relax and don't need to try covering techniques? If so, that's where you'd ideally want to get to with your bf, as someone so close to you. It's entirely doable! But of course that first convo is going to be quite something. The only issue you \*might\* have with him is something like "but what do you mean, I've not heard you stammering." You may have to patiently explain what an interiorised stammer is (or whatever language you want to use to explain all the efforts some of us go to to keep it hidden!) If that's the case - don't take that as evidence it's wrong to tell him. He cares about you clearly given how long you've been together. There's just the small matter of all the shame around it to dodge - that job is ongoing and eternal with stammering, I'm still doing the same at 50 years old! So yes - on whether he'll be mad, first, he won't be! Second, that again is a conversation around why we try to hide it, how the stammer can make us feel, what it's like living with it every day. As you say, you'll probably cry, and that's also totally OK and understandable! If it helps, I'd suggest watching the two Brene Brown videos on, first, vulnerability, and then on shame. I rewatch them repeatedly before I have to tackle a difficult moment like this!