How do you know if a thought is intrusive or not? I feel like I thought something on purpose but I’m not %100 sure…

I been dealing with intrusive to the point it feels like I think them idk what to do I feel like a monster.

Earlier I had what felt like an urge but I’m not sure. I’ve had urges before but this felt different as the object was in front of me (not intentional btw) , I’ve been quite stressed lately and my OCD is latching on to that. I had an urge to harm and within that I had like 2/3 intrusive images that came to mind, I couldn’t rationalise with it, I felt “stuck” when I came out of it I felt scared immediately was trying to work out why I’d even think of doing that & was very upset. A while after I keep getting thoughts like “say your goodbyes it won’t be long until you act out” I cried to my boyfriend and told him everything. How do I know if this was intent vs intrusive urge?

I wanted to ask if it is possible to purposely think of an intrusive thought and then shifting your mind instantly to something else? Is it still an intrusive thought if you have been thinking of it 'purposely' for a second? I dont know how else to explain it, but it felt like I was purposely thinking of it. Anyone else had similar experience what happened during intimate moments like masturbation I feel so ashamed cuz the thoughts are so bad they're either about family members children and stuff like that it feels like I think it I just want to know if I'm not alone I feel like a monster because it feels like I thought these things or like I did think these things and I don't know what to do I feel so ashamed and grossed I need help I just want to know if anyone had a similar experience to shed light on because I don't know I feel so isolated