@concernedhusband,
No. It's wisest to end that friendship. It's your marriage that is at stake. How you feel about what happened is what should matter here. She can find another study partner. This about your needs, too. The marriage has been threatened by this infidelity. Are you and have you been faithful to her?
Out of curiosity, what is wrong with studying at the library instead of someone's truck? Where is the common sense there?
Furthermore, you two clearly have some marital trouble. There'd be no fidelity issue if she and you had no issue with your marriage and intimacy. Either work that out between you two..and/or seek counseling. In the meanwhile she might seek friendship and study-buddies elsewhere, 'cause that well is polluted.