Ultimately it is your car and your dough. If you have put 68K on it in 3 years you are certainly getting your monies worth.
Cars do require maintenance and a 10 yr old with 98K will continue to do so.
If it were mine and I wanted to keep it I'd:
* Thank the helpful shop for their advice and fix the exhaust myself for $200. Put the other $4K in a college fund for my 1st born.
* Repair all other minor issues to keep it in good condition for another $200-300.
* Consider a clutch/IMS job if it has not been done yet.
And then drive it for another 100K miles.
If this just sounds like too much trouble, it's time to sell it now.