Lots of old friends and exes and people she works with get in touch and asks if she's single, like a weekly occurrence for a while. Regularly talking to many of them on fb messenger or whatsapp. She even told me she text an ex recently just to say hi. . . I asked her once why so many people ask her out, she said she had no idea and told me she was going to stop telling me about it. Which she has, so it either doesn't happen anymore or she just doesn't tell me. All just left me feeling very insecure
Yes - it would leave you feeling insecure which was probably the aim.
Think about it for a second - how many people do you know in real life (as in grounded in reality) get asked out and hit on all the time?
SIMPLE ANSWER: NO ONE
MORE SUBTLE ANSWER: ALMOST NO ONE UNLESS THEY ARE ACTIVELY ENCOURAGING IT
There are a number of reasons for this. Humans don't like rejection. It takes a lot to hit on someone and ask them out unless (a) you are a hound dog who doesn't care and are just looking for any hole in which to squirrel yourself away or (b) you have had super positive flirty come-on vibes.
Really super-attractive people (model types that very few people look like) don't even get hit on like that because others are intimidated.
SO - the bottom line is (a) it's untrue that she is getting hit on all the time and (b) she is telling you for a reason - to make herself appear more attractive to you and make you feel you have something to lose.
And it's worked very well.
I was once in a relationship like this and it really saps your self esteem. It's only when I independently discovered that one of the women he had gone on and on about fancying him and trying to get him on his own (he went to great lengths to keep us apart) actually wouldn't touch him with a barge pole and thought he was an idiot did the light dawn.
Be careful of someone who is deliberately pressing your insecurity buttons. Nothing good lies that way