This. Lying or hiding things always goes poorly. Have a discussion and set reasonable limits so that you enjoy your hobby and she supports your hobby.
As an example- I've cut back on spending on the areas that are not that important and spread my mustang projects over time - both of these factors allow me to have allowed me to build a MM
suspension, full Bolton, maxed out short block 2v. There is always more to add on ..... (planning out forged internals now) but everyone is happy because we are both inside our budget and get to buy the fun things we like.
10k in motor parts / install / tune is a major investment. Spread it out and keep her in the loop about your plans. If you set a budget with her you will be surprised how much you can do and how happy she will stay.