I think my boyfriend is still lying to me
Why do you think your boyfriend is lying to you?
I have some evidence to justify my claim.
Have you spoken to him about why you think he's lying? If you have evidence, then you should share it with him - you may be misinterpreting what you know or not have the whole picture.
I will deal with him when I catch him.
Why don't you just talk to him first if you are suspicious? It will be healthier for your relationship if you do.