Let's look at things a little differently. Despite what you think, or what you wish - you can't "own" another person. Even a married person is free to make his or her own choices. You can't make them do anything that they do not want to do. The only place you can look for trust is within yourself. You need to see things from a different perspective - that YOU are in control only of YOU - nobody else. Taking responsibility for oneself is the highest way to live. Trying to make others do that for you is the lowest. You deserve better than this.
Don't place your well being in someone else's hands. What if they don't live up to it? Instead, come to the realization that you are worthy of your partner's fidelity, and expect them to abide by it. If they don't get it, you'll understand that you've simply made a mistake in your belief of who they are, and you can move on to find someone that DOES mean it, with your head high, and your self-esteem intact.