SIL's birthday

So my brother's wife is celebrating her birthday at this place where they'll give painting lessons and wine. Everyone has to pay $40 each to attend this thing. Lately my husband and I have been on a really tight budget and we don't have $80 to attend a painting class and drink wine. It's probably not a lot but I rather spend that amount of money on something we both love doing. Well today I respectfully declined her invitation and she texted me saying how I should at least go so I don't look bad 😒 Everyone will be there with their partners and I I guess I could go by myself but I sure as hell don't want to be the only one without my husband lol I haven't said anything to her because I don't want to start any drama, but it made feel really uncomfortable. What would you do?