Forgiveness isn't instant. It can take days or even months. The most important thing is to start the process. The first thing you need to do is to acknowledge that you've been wronged. Secondly, express how you feel and be honest about it even if your feelings are negative or horrible. Thirdly, say that you forgive the offender for the specific thing they did or said. Fourthly, thank God for his grace that has also brought your forgiveness. Next, say that you'll not hold the offender accountable for your future sufferings. Lastly, receive healing for the pain you feel. Only Jesus can heal that pain. The offender can't and time won't. You can go through this process during prayer or with a mature and trusted friend.