Rebuilding trust is never going to be easy. Whilst this is not the complete answer, these are some things that will certainly help.
1. Say what you are going to do and then do it. If something gets in the way of you doing it, let the other person know and tell them of the change in plan. This goes towards answering the question Can I trust that you are the sort of person who keeps their word?
2. When your partner raises difficult topics, be curious and caring about what they are saying. If possible, let go of defensiveness, show that you have really listened to your partner by reflecting back, in your own words what they have said and show that you get their feelings. Doing this shows that you care about the other person and the relationship.
3. Curiosity and caring about the other are two important aspects of the early stages of romantic love. Working to regain these key attitudes will help develop trust.