I don't know if I trust my boyfriend
Why don't you trust him?
I often feel like he does not have my best interests in mind.
It is hard to trust someone with your heart but without trust the relationship won't succeed.  Your partner will feel hurt about your lack of trust and your relationship will end.
It's fine. I'm going to dump him.
If that's how you truly feel then that is fine. It's better for a breakup than to be with someone you can't trust.