Limited info. Where on the belly is it? It looks like, did you in fact dry heat? Under the pencil mark, how deep is the crack, fret, stress, or whatever you want to call it?
If it was me, if it is located anywhere on the working limb, I would scrape down to see how far it goes. May not be as bad as it seems. If you can get to the bottome of it, take both limbs down and tiller for a light bow.
Then............................4 layers of sinew. Sinew it up, let it dry, minor re-tiller and you've saved your bow.
But it's a gamble and it may go bust.
The best bows are the ones that you've had to solve problems with. The better bows are the ones that failed and you learned something.
Good luck.