Friend being strange with me now she's researched my financial situation

She sound unhinged. In your position, OP, I'd be absolutely livid.

What you own/earn and how you organise your money (well, by the sounds of it - well done) is none of her business. It's no one's business, in fact.

I am also single, perpetually so, and I have organised myself in a similar fashion to yourself. I was able to pay off my student loans, buy my own flat, and then another to rent out (makes no money, it is similar to your rented room covering your part of the mortgage).

It doesn't feel like "luck" or being "moneybags". It feels like months and years of monthly saving, seeking advice, making sensible decisions, always putting bonuses into savings accounts, never taking big holidays, always keeping something somewhere in case a boiler drops off the wall...

I think you need to be assertive and say to her "What you have done has made me uncomfortable. My financial set up is no one else's business, my "net worth" has nothing to do with who I am, how I behave or my worth as a friend in this group. You have far overstepped my boundaries and I expect an apology. If you are unwilling to recognise your upsetting behaviour, I will be rethinking my contact with you."

You have every right to defend your own little bubble of security and tell someone "your behaviour is not ok for me, so I chose to walk away from you".

Tell the group or someone in the group what she did and that you found it weird
She's probably done it to them too.

Put on your best Lady Bracknell voice and tell her it’s frightfully vulgar to talk about money.

I don't think the value of your assets or hers is relevant here. I also don't think it's your responsibility to check on the well being of a person who is behaving so rudely towards you. Creating distance is more in your interests. Who knows how she would behave if she thought she could confide in you?

Her behaviour is very odd and a bit stalkerish so please don't encourage her.

I wouldn't be passive aggressive with her and whilst I think humour can defuse a tense situation it also diminishes the weirdness of her behaviour.

I think if she comments again I would be quite assertive with her and tell her it is very strange for her to have attempted to calculate your net worth, stranger that she would tell you she had done it and rude that she keeps referencing it. Tell her she is mistaken but it doesn't matter because it's none of her business and not to mention it again. And then every time she mentions it just walk away without a word. No one sane would think her behaviour is acceptable.

OP I'd just have a couple of retorts handy if she says anything again along the lines of:
"Moneybags ... I wish, the bank owns everything haha "
"I can't afford to repair my car/fix the boiler let alone buy that/do that"
"This designer dress came from vinted ! Amazing bargains on there"
"I love my bobbly jumper, I buy everything second hand because I don't have much spare cash these days"

None of it has to be true but just to deflect the conversation off the money point and let her know you're not as well off as she thinks. This is for the scenario that you don't want to cut ties etc as she's in the friendship group. Obviously she's been very rude and nosey so you'd be entirely within rights to cut ties !

You're getting distracted by thoughts of whether you are rich or not, or how you compare in other ways.

She's controlling your behaviour. Stop letting her drag you down to her level.

The focus should be how are you going to put up appropriate boundaries now you are aware of the fact this woman is not a friend and is behaving extremely strangely? To research you is odd, to tell you is off the scale - but your response is also quite odd as you are joining in the comparisons.

Jealousy. I've found that when friends are not very kind or let you down badly it always come from jealousy.

I was badly treated this summer by a decades old friend and I think deep down she was jealous of me and she was waiting for something awful to happen so she could remove herself and enjoy my misery. I do not speak to her but I would like to know how long she was waiting

I'd either remove myself from her or have less to do with her.

You get this Op. DH and I had a small portfolio of 5 rentals and live in a pretty large home (it’s secluded with its own drive). My own family often say “you have loads of money you can afford X” we never moan about money, we’re fruggle not flash. It’s jealousy.

Op how does she know the addresses of all 5 properties ... I barely know the actually addresses of my family.. I just know how to drive there.. I wouldn't for the life of me remember door numbers and post codes of family in order to research them, let alone someone's 5 properties when I'm not even that close to them.

Call her out on it in front of others in the group. Ask if Sally has been researching them online the way she has you and put 2 and 2 together and come up with 5. Ask if she has nothing else better to do with her time. She sounds like a creep.

She’s unbearably rude.

Next time she brings it up I'd ask why she's so invested in your financial situation?

Ok used to have a friend who kept asking when I was going to get married so I started asking her when she planned to get divorced. She stopped asking.

i actually nearly laughed that she felt the need to cost the dog- on my best day I’d have said ‘Rover’s priceless to me, what are you saying?’😅 Some people just can’t see beyond money, unfortunately you’ll hear a lot more of ‘but you can afford it!’ Bil is well off and have heard people say so much ‘but why doesn’t he just pay for that’ eg if he fixes something or goes without instead of buying. They also assume he’ll pay for everything and wants to burn money. I’d hate to be rich (I know you’re not, but she sees property and worth being more than hers and obviously thinks you are!)

Sally is the type of person who judges what people are “worth” by how much money they do or don’t have. I find people like that are best avoided.
But, money makes people weird. I paid a large amount of money for an operation for my dog. I bumped into an acquaintance who had heard about said operation and asked me how much it cost. I didn’t tell her (I didn’t tell anyone, why would I?) and she responded that it was obviously expensive and I was “stupid, selfish and self centred” because that money could have helped HER out? I barely knew the woman! I’ve avoided her since.

What on earth! Sally would be blocked immediately. What the f?

Her calling you money bags hasn’t broken up the group so just say, “You’re not my accountant, nosy rosy.” in a very cheery way. If the group are your good friends why might even chime in and ask her why she keeps referring to your finances. If you get dropped for challenging her they’re not people you want to be around.

I think I know Sally. She’s probably saying quite a bit more behind your back and she’s an arsehole.🫤

Your so called friend is spreading malicious info about you. She's hugely jealous. Drop her and don't be quiet about it. Tell people you earn little and the houses are all mortgaged so no cash in them. That you dropped her because she was spreading untruths about you and that you just can't trust someone who does that.

"I hope you're not going to ask me for a loan/gift/whatever because, as you have seen from your nosy investigations, I have assets but not free cash. Don't contact me again."

Well you need to own that you are wealthy and fortunate compared to many, many people. You just are.

But she is behaving absolutely dreadfully.

Sally doesn’t sound like much of a friend. She has been snooping on you and makes snarky comments calling you moneybags and telling you what you can and can’t afford and what to wear. Sounds like the green eyed monster.

This is really weird, stalkerish behaviour. I would be distancing myself from her.

I'm extremely surprised that she knew the addresses of all 5 properties in which you have an interest unless you've been oversharing details about your finances, especially as you say you're not particularly close to her within the group.

We own several properties (not DH's wealth in case that's relevant, but just hard work by two of us, with me out-earning slightly). Friends in a similar position to your 'Sally' would likely not even know how many properties we own, let alone where they are, to be able to look up their value. And school-gate acquaintances wouldn't have much of a sense of our worth from outward appearances (only one cheaper car, often walking or getting public transport for environmental reasons, etc.).

The lesson I would take from this, OP, is to make sure you're not oversharing. Either that, or it's not true.

For her to try and work out how much you're worth is totally bizarre, to admit to you that she's done so is madness. She's clearly insane and/or very insecure.

There is no way I'd have this woman in my life.

This is a situation where directness is called for, I think.

"Sally, why are you obsessed with how much money you think I have? It's rude and weird and it's making me feel uncomfortable. Please stop."

Your net worth is 120k?
That is not particularly high. Most of the people I know, even with 1 house would have more equity from that. So its very odd that she is annoyed at this. What a weirdo. I'd be swerving her going forward.