Am I overthinking or is it assault?

I know I asked this question before but I have a tad update. I have been dating this guy for 7 months. We were making out and he found a condom in the back of the car. I thought we were gonna have vaginal sex. He surprised me by putting it in my ass. I never had anal sex in my life. I was against it until I did research on it then told him I was up for it a while back. He didn’t tell me he was going in ass. He put it in for a few seconds. It didn’t really hurt when it was inside me (he had a condom on) but when he pulled out I felt the pain. I told him no more that really hurt it was uncomfortable ouch. He then moved me into a better spot in the back of the car. I asked him if he meant to get into my ass and he said no I said bullshit and we both laughed. I then thought we were gonna have regular sex. He tried again I saw him trying but he only got the tip in and then stopped. I was in shock like wtf. He probably realized I was saying no again and wanted vaginal sex and he had to finish as well lol. I was genuinely upset. After it was over I was truly scared and kept questioning him. He told me the reasoning that he wanted to try something new. And that after I said no it hurts he moved me into a better spot to see if it felt better. He calmly answered my questions in a nice manor. He said it’s not sexy to say every single thing ur doing during sex and I should trust him and his intentions by now. Today I told him I was upset and my ass was kinda sore lol. I told him how we need more communication regardless of it not being sexy. He swore to me on something he never swears on unless he truly means it. Should I believe him? I did loose some respect. So was it sexual assault? Or was it a misunderstanding? I also lost my virginity to him. He has pressed his luck before in the past but always stopped when I said no. But the other night was a tad different. I wish he communicated more during the time it happened and not had to wait after. What do you all think!
Am I overthinking or is it assault?
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