Great you have insight into how childhood rejection and abandonment are likely coming into play here. Whatever the outcome, this relationship sounds like a catalyst for you to go inward and heal the wounds, and to give yourself the love and validation you deserve.
With that background, we can grow up making massive allowances for other people's behaviour (grateful for whatever attention we get). And we can also project our insecurities onto others. You seem to be weighing up the two possibilities here (and being very open to and gracious about the feedback you're getting).
Only you can know your gut response. But it might be helpful to know that, in my experience, there's a number of red flags in your partner's behaviour (if I've understood you correctly):
- the whirlwind romance and moving in
- why ask you to review the FB photos if he'd undertaken to remove them? Either he's tech-savvy to check the page himself as it appears to others (as s.o. has pointed out) or he could ask you to load the page and check it himself. Was he testing your reaction to the 'snuggling' pics?
- great that he is on good terms with the ex and her parent/s and that the children don't have divided loyalties - but she had an affair, you say. If she needs a man's help, why doesn't the new partner or the adult son/s provide it?
- why does the ex even want her discarded husband to do her odd jobs, and what's the pay-off for him? At the very least it suggests he has weak boundaries where she is concerned.
- you say he pulls away if you express disquiet. That would draw you back, wouldn't it? (rejection hurts!) Does that work in his favour, or yours or to the benefit of you both?
If you find you feel in the wrong more than you feel reassured, you might consider putting some distance between you, as people have suggested. If he really loves you, he will understand. If he resists, he may be invested in having the partner to save face (at the very least).
You come across as a loving and respectful person who takes responsibility for herself and her actions, and who has successful relationships with family and friends. How much do you deserve a partner who reflects that back to you? 100%.