I accidently bought myself a 250 e- gift card from my apple credit card that is currently sitting in my apple wallet and it will only let me purchaes things from Apple. I thought I would be able to use it for apple pay but I cannot.

Normally once funds are in Apple Account balance the only way to get them out again is to spend them.

From: Check your Apple ID balance - Check your Apple Account balance - Apple Support -->

"About unused Apple ID balance

You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards, or unused Apple ID balance for cash, except as required by law. If your jurisdiction allows for refund of redeemed gift balances, you can contact Apple Support." Read the support article for more details.

The above excerpt only mentions gift balances as being eligible for refunding, and only in limited places where laws may require that. Read the support article for more details.

If you still have questions or problems:

Refer to this document for ways to contact Apple —> Choose your country or region - Official Apple Support

Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service by telephone —> Contact Apple for support and service - Apple Support

Re: “… I wanted to use it for apple pay or use it like cash … “

Unfortunately, an Apple Gift Card can only be used for Apple goods and services … and it is generally not refundable.

See:

What you can buy with your Apple Gift Card or Apple Account balance - Apple Support

and the final paragraph of this:

Check your Apple Account balance – Apple Support (AU)