You can forgive someone and still not give them a key.

Forgiveness and access are two separate decisions, and people get talked into treating them as one. You can put down the anger, stop replaying the whole thing, and genuinely want somebody to be okay, without handing back everything they used to have. Keeping some distance is not a grudge. It is an honest account of what has been demonstrated so far.

If you have forgiven someone and still feel wary, you are not being petty. Offer the smaller version of trust and watch how it gets handled. What happens with the small thing tells you whether the bigger one makes sense yet.