let in

verb4

1. •
   To let someone or something come in; to admit someone or something in.

   • He opened the window to let in the air.
2. •
   To divulge one's inner thoughts to (someone), making oneself emotionally vulnerable to them; to open up to (someone).

   • So tell me when you're gonna let me in / I'm getting tired and I need somewhere to begin — 2004
3. •
   To associate with.
4. •
   (slang, no longer used) To cheat or victimize.

   • He let me in heavily.