Want to move out to save marriage. How to persuade husband without hurting him?

Me and my husband have been having some problems in our 4-year marriage and recently all I can think about is to move out for a few months, to try what they call a "trial separation." I fell in love with my colleague, had an affair with him, then came clear, cut all contact with him outside of work, apologized profoundly to my husband, but my husband still doesn't trust me, for good reasons. I know I'm a terrible person, but everyone makes mistakes, I did all these at a time I was very vulnerable, when I was severely depressed (am getting treated now) after my father's death from cancer and the love and affection my colleague showed me was just irresistable. I want to fall back in love with my husband, but I cannot now despite all my efforts, and like i said he has trust issues and wants to restrict me, have more say in my life, including who I go out with and what time I should return home if I go out with friends. I feel like I'm suffocating and need so me time to be alone, to be just with myself, have some breathing space. So I thought that maybe moving out temporarily could be a solution, maybe we can start dating, I cook for him, I miss him and fall back in love with him. But how can I persuade my husband without hurting him and without sounding like bull****? My colleague's wife lives abroad and is 8 months pregnant, I show no interest in him, but my husband is still suspicious since he thinks that the man will seek a woman's company since he lives here alone.
I don't have the heart to ask for a divorce, because I fear I might end up being alone and forever lose the wonderful husband that I have, but whom I can't appreciate enough. I feel like if I end up alone and he finds someone I'd be jealous as hell.
Please only reply if you are going to make a real contribution, really the last thing I need is to hear how horrible I am -- I already know that.

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