Without going into your particular situation too much (if I did that, I'd have to know a lot more about you, for, possibly, no real benefit for you), I agree that memories are a good thing. All of them. Even the really horrible ones. If that doesn't make sense, please bear with me for another paragraph or two. If it makes a weird kind of sense to you after you've finished reading my post, that's perfectly find. In fact, I'm not even going to expect that you find this all perfectly logical. After all, logic hasn't helped you get rid of all the bad things. Perhaps it's better to set logic aside now. Just get a feeling for what it all might mean, and leave it at that.
How do you learn to swim? How do you get a phobia of spiders? How do you feel bad about a situation? All of these work along the same lines: you have an experience and you make a judgement about it (perhaps through a process of contemplation, perhaps it's just a feeling you get). These two factors together influence the way similar situations will affect you in the future.
Now if you block off the experience, or the memory of the experience, as you suggested, you may no longer be able to recall what happened, but the judgement will probably remain and continue to influence you. If, on the other hand, you were to change your judgement of the experience on a fundamental level of your mind, you would still remember everything that happened, and remember that you didn't enjoy it very much back then, but that the experience contains a valuable lesson for you, a lesson that will completely change the way you think about things and will leave you more confident, more sure of yourself and your life, and, perhaps even more importantly, perfectly fine.
At this point I can't tell you which kind of judgement or lesson that would be, because I don't know the situation. But the good news is that the level of your mind on which these things happen does know, because it's a part of you. It knows, and I don't know when it will find this important lesson that it hasn't been looking for before now, but even if it takes a couple of days, at some point you may find that, very suddenly, it clicks in your head and you feel different. Or perhaps in a week or three you suddenly notice that this experience you used to feel very bad about isn't really a big deal anymore. In either case, it usually happens precisely at the moment you least expect it, so I really couldn't say how quickly it will happen.
All that said, I wish you all the best in your quest to use the power of hypnosis. If anything interesting happens, I'd love to hear about it.