I need someone to tell me that I'm not going crazy and it's perfectly normal to feel this way after being betrayed

Me and my ex are deciding to get back together after three months of being separated due to the fact that I caught him talking to my best friend and vice versa, after 3 1/2 years I decided to forgive and forget in a way but somehow shit still bothers me in a previous post I noted that I did see something on his phone where unblocked this other girl that used to be my friend and liked her pics which is probably not a big deal but there's aback story to it anyways I've been texting him but it just feels like fuck I can't do this you know? Am I being fucking psycho or are these emotions I'm currently feeling normal? I just want to be able to trust him but it just keeps hitting my chest I just want him to understand that it's not easy and the healing does take time