I (27F) caught my fiance (27M) cleaning his phone port with my toothbrush

I (27F) caught my fiance (26M) using my toothbrush to clean his phone port.

So, I walk in from doing some garden work, I need to use the restroom really badly. I walk in, and immediately see him using my (pink) toothbrush to clean his phone port, which has not been working the last few days. I immediately freeze, feel sick to my stomach, and feel like I'm going to pass out. My hands start shaking, and honestly the feeling of betrayal and disgust really overtook me. I was immediately overwhelmed, and told him he needed to buy me a new toothbrush. He look on his face. I just can't unsee how guilty he knew he was. I then tell him that I am honestly so disgusted and can't believe he would do that to me, specifically choosing my toothbrush out of the two options (his is green). He says that it is simply an accident, and that he was overwhelmed with his ADD and didn't even consider what he was doing. He went as far as to say that it was hypocritical of me NOT to accept his ADD answer, because my ADHD often causes me to do inconsiderate things, that often upset him. I do not like feeling like I'm being gaslit, nor do I feel I should have to accept that it was simply an accident. If I hadn't caught him, he likely would have returned my toothbrush to its holder. What other things do I have to look out for? But, I do often inflate intense feelings and emotions due to my ADHD, and have to be very cautious of that as well.

Insight always appreciated.