Let me put it this way, I've been through three relationships in my lifetime. The hardest and most destructive one to me emotionally was with a cheater. You live together, share your life, tell your secrets, hopes and desires. This is the person you trust, share bank accounts with, and share your bed with. Nothing prepares you for the moment you walk into your home and find your partner in bed with another.You now have a choice. You can accept his story of whatever reason he brought this person to your home, and your bed. OR you can pick up what is left of your pride, self respect, and life and move the hell on while you still have a chance. No one said it would be easy or fun.
HH you said you were out there looking for someone who you could trust. Doesn't sound like after he has cheated on you, you are truly ready to forgive and forget.