Once the genie's out of the bottle it can be hard to put the lid back on, but you don't have to take this any further if you don't want to.
At the moment you're in a situation where you unexpectedly saw a face in a photo from your childhood that made you feel scared. This feeling may be due to an experience or experiences in your childhood that you may have chosen to forget.
Alternatively, the face you saw in the photo may have reminded you of a time in your childhood when you were unhappy, and it could be that you have merely associated this face with that period in your life and that he did not cause you any harm.
Of course, since you saw the photo(s) you've thought of little else, your OH has chipped with his views and, for good measure, we've put our two pennorth into the pot too so no wonder it's right at the forefront of your mind at the moment.
However, give it a few weeks and meeting the demands of the dc, OH, etc will ensure that the photo, the face, and that time in your life, has gone onto the back burner of your mind and you'll only think about it occasionally, if ever.
If you want to speed this process up, simply replace any thoughts that come into your head about this matter with others - in other words, just refuse to think about it or let it worry you.
On the other hand, if you find that you're remembering things about that period of time and that the memories are making you feel unsettled, you might want to consider using the following exercise which you can perform as often or as little as you want:
Find a quiet place where you can sit alone for 10 minutes without interruption. Remind yourself that the owner of the face in the photo has no power over you; you are in a safe place and he cannot harm you in any way.
Visualise your 8* year old self and give her a big cuddle. Tell her that she need have no fears or worries for her future because everything is going to work out for her; tell her that she'll do x y and z (list some of the positive moments in your life) and, by time she's 30, she'll have dc of her own who will bring her enormous happiness and joy.
In this way, you are giving yourself (via your childhood self) permission to unlock any memories that you (they) repressed. After you've finished 'talking' to the child that you were, come back to the present, remind yourself again that you are in a safe place and that nothing from the past has the power to harm you, and go about your usual routine/chores/etc.
If you use this exercise I would suggest that you resist the temptation to tell others what you're doing/have done, and don't dwell on the past at other times.
I've chosen 8*years old as you were no longer living with your dm's boyfriend at that age and any unpleasant memories that you may have repressed were newly buried, so to speak, and will be easier to 'dig up'. If an image of the 7 year old you appears in your mind, talk to her and give her any comfort she needs.
I'm aware that this is a very long response but, in all conscience, I can't make it any shorter without doing you a disservice.
You mentioned 2 memories; could you clarify whether you've always had them or did they come to mind after you saw the photo?
You also mentioned recalling a friend's house in great detail. Are you still in touch with this friend? Other than your dm, are you in contact with others (relatives, neighbours, schoolfriends etc) from that time who may be able to help you shed some light on that period of your childhood?