Caught my boyfriend using Tinder behind my back, am I stupid for giving him a second chance?

Last Friday I catfished my boyfriend, because I saw something on his phone what looked like Tinder, but I wasn't sure. I created a fake profile and it took me about a week to find him. I swiped right, and we were a match (again, because I actually met him there). I received a text: Hey, how are you sexy?

I confronted him and he kept saying it wasn't him and that it must be some kind of joke. He wouldn't let me look in his phone, because of a "matter of trust". Wasn't buying it so after about three hours, he finally confessed. He said he did it because he was insecure and needed some kind of ego-boost. He cried for about an hour, said he never met with any girl or exchanged numbers, that it was going on for two weeks, that he was just chatting and ended up comparing all the girls to me and realized I was still the one for him. I watched him delete the profile.

Seems like all the other "help my boyfriend is on Tinder" cases, but this one's a little different, because I have borderline personality disorder. Not a very heavy version, but life's been tough on us lately. He is always there for me to help, but most of the time it's hard for me to accept his help. I reject him a lot. Won't let him hug me when I'm down, get triggered easily and start fights over stupid things. I know it's wrong and I'm in therapy for that. Sometimes he joins my therapy sessions and we talk about it a lot. He's such a good guy, I couldn't wish for anyone better. Except for this Tinder matter.

Now he's trying to show me that he loves me, that I'm good enough for him, that it was a stupid mistake and it won't happen again, that he has no idea what he the hell he was thinking. Keeps saying he's sorry and it seems honest to me. We talk about it a lot, also about what I could do to make him feel appreciated. I really want to learn to trust him again, but it's hard. I'm really hurt. How do I know it's not going to happen again? Am I stupid for giving him another chance? What should I do?
Updates
+1 y
Some background information: We're together for over a year now and we live together for almost six months. I'm 24 and he's 27 years old.
Caught my boyfriend using Tinder behind my back, am I stupid for giving him a second chance?
Post Opinion