Relationship trauma

It's my first time posting here... on this forum and I really don't know if this would be classified as a "trauma" but it impacted me in such a way that it continues to affect me in my relationships and my life; it happened in April/June of the other year, I met this person on the internet through my ex (who I don't care about anymore) who was his best friend, anyway, we talked and he was like my shoulder to lean on (because he was also my ex's friend and my friend) when my ex broke up with me, long story that I don't want to tell but it wasn't a nice relationship..

We started talking more and we were friends, months went by and in July (I think) he confessed to me and told me that he loved me, although at first he wasn't able to confess, he only made innuendos on ***, which I quickly deciphered and knew he was talking about me.

Anyway, I told him I wanted to think about it and I took some time, I started to tell myself "I don't like him... I'm not attracted to him... at all" but a part of me was "manipulated" by the pity he gave me, sometimes I also feel like he could have lovebombed me; anyway, I said that I liked him, all because of... pity, which I regret and it's not right that I did it but it was difficult because If i told him that maybe I didn't feel the same he was going to feel bad and had self-destructive tendencies.

We were boyfriends.. and it was hard, at first it was "nice" very loving and romantic, it was, I won't deny it but it was also traumatizing and terrifying at a certain point,,, he smoked and sometimes drank at an age that wasn't normal, we were 17 (I'm 18 right now) and smoking was his way of dealing with his problems, he... was very complicated and I was worried like the person that i am, I didn't want to see him in a bad way either but it was difficult to deal with that because, they weren't my problems and, I didn't know how to handle it, it wasn't a problem that someone of 17 had to handle and I know that he told me that I didn't have to worry or even deal with his problems but, as a couple, it affects you too.

Then, he was also very obsessive to a certain point that he told me that he was going to kill anyone who hugged me but not my best friends... and it was scary, my alerts had already started to rise and get worse, I didn't trust him and I was afraid of him as the months went by, it was no longer healthy.

Also, he was hurting himself, he suffered SA, his father was... I don't know if I should talk about this but he was a murderer and a cannibal, which left me even more terrified and speechless; In his family there was incest and problems, he liked gore, he liked serial killers and other terms... I wasn't like that, I wasn't like him and I didn't want to be like that, I didn't feel safe and much less happy... I don't know why I lasted so long with him (we lasted from July to December but since August I didn't want to be with him anymore), maybe I just put it aside and concentrated on how he was good to me and other things but, now that I see it, it was too dangerous and it was noticeable by the way it affected my mental health and sanity.

The good thing is that I never showed him my house adress or gave him personal information like names of my family or friends, but he did know what I looked like, he did know the state where I lived but he told me that he wouldn't hurt me and such, which I believe but still, it scares me and I can't stop thinking that I want to avoid him at all costs, I even blocked him when we broke up.

And when we broke up it was difficult, I told him that I didn't want to continue and that I was tired, I remember that I told him that I was scared and he always said that he was going to change but I didn't believe him; He finally said not directly that he didn't care about my mental health and that he wanted to continue being my boyfriend, I got angry and began to vent completely and tell him that if for him I was an object among other things,,,, I don't know what I expected from him-

But in the end I'm already far away, far away from him and I moved on so I know that at least he's not going to know about me anymore,,, I told him that we could be friends but it was already uncomfortable and I was still scared so in the end I blocked him, that was my decision,,, but it does continue to affect me in how I see my friends, in how I see love and the fear that now gives me to trust again and give my heart to someone who is not worth it (not to mention that I have already had MANY bad love experiences, so it is best that i stay single) and every time I have a new interaction that thought comes up... if they are going to be like him, if they are going to make me trust them to then show me their true self.. it is difficult for me to trust strangers or unknown people again and right now I only keep talking to my circle of friends that I've had for a long time, it's hard for me to avoid those thoughts.