How to untangle my out of control tomatoes?

I've never grown anything in my life and i planted a little grape tomato plant against the fence in the driveway a few months ago. Now it is a massive crawling monster, heavy with fruit. I never put a proper trellis behind it, just sort of wrapped the first few long vines around a few sticks and forgot about it. It's a complete MESS now and i feel so guilty about all the beautiful tomatoes going to waste. I just cut as many as i could off but there are countless new green clusters trapped in there. I'd like to get it under control but i don't know how to untangle it without breaking the major vines. Can i even try to get a trellis in there if it's in full maniacal bloom or do i have to cut away and start anew. I'm clueless and overwhelmed. Help!