lottery We are all strangers on the internet. Clearly you've posted about something that is off and we don't see how you are together on a day to day basis when things are good. Absolutely people on MN can only respond to what you say.
Having said that, you are in a very vulnerable position and you clearly feel something is 'off'. Your DP should take that seriously.
Looking are your comments:
He takes on a lot of extra curricular activities without talking to me first.
Does he afford you the same luxury? Is he expecting you to take up slack as a result? He will have more free time I assume because he has his DS EOW, but could be an issue if you're planning DC together. (Also, to be pedantic if he's adopting your son...etc.)
If we run into old friends of his he doesn't introduce me.
As you say, this might be friends from when he was with ex. Not great, but doesn't sound like a massive deal-breaker if he's telling his friends / colleagues that he sees now how wonderful you are.
He doesn't let me have any of his passwords (he has all mine)
DP and I are bit lax with these things, but tbh I don't think couples have to share all passwords. If he's a security expert I wouldn't expect him to share passwords or to want a password of mine that he wouldn't give me. As long as this doesn't impact you directly (e.g. he won't share the router password, or the joint online gas bill or whatever) I don't see that this is an issue. Sharing too much can cause problems in itself.
He doesn't make any effort with my family.
Red flag here. Is there a reason for this? Is it differing backgrounds / expectations (my DP hasn't always made enough effort with my family, but then less effort is expected in his family, so we try to keep each other right
)
If I try and talk about serious stuff he tries to have sex with me
That would worry me. He's a grown man with an fiancee, child and ex-wife. He has to be able to hold grown-up discussions.
Ultimately OP only you can decide how important this is to you, but you are financially vulnerable.