I'm so sorry for your loss. It seems much more difficult to be with someone you love and don't have to worry about what people think and then having to start over can be tough. But even people without ostomies have to deal with the discomfort of getting to know someone new. I'm also sorry for the long post.
There are so many previous posts on this site with multiple opinions. I'll share what I've learned from myself and from other people and apologize in advance if it sounds like I'm talking out of my arse.
After my surgery at 23, I was scared that I wouldn't be able to date or be naked in front of another woman ever again without feeling like I was grossing them out. But I was confident, maybe even a little cocky. And I like you, would tell people right away about my ileostomy. Having an ileostomy didn't stop me from being me.
Most of the time, I wasn't even trying to date a woman, more like meeting a woman at a bar or social function. And during the course of the conversation, I would bring up the fact that I'm an ostomate. I would make it a funny conversation along the lines of, "Oh, I had this surgery when I was 23, I have a scar from mid chest to my groin and I don't shxt like everyone else anymore." I honestly NEVER had a woman stop talking or associating with me because I had a bag. And dating or casual experiences were never an issue to me.
Now, that is my experience. From other posts I've seen here, men and women both have a lot of anxiety about dating with an ostomy. Some because they have problems with leakage, self body image issues or just feel gross, half a person or broken. Others just have a problem with rejection.
I've also read that it is easier for a man with an ostomy to be accepted than it is for a woman, as women, not all of them, aren't always drawn to a man because of his looks. Opinions vary. Men on the other hand, not all of them, are usually drawn to women who are attractive or aesthetically pleasing to the eye, first and foremost, and then later attracted to other qualities about a woman.
Again, this is my opinion or summarization from what I've read in the forums here, and my own personal experiences. Your own experience will depend on what you're looking for. Be it casual dating or if you're looking for a long term relationship. You may have to get through a few bad apples before you find a person that is comfortable with it. Then again, another mister right, may be right around the corner.
Don't give up trying though. Put yourself out there. If you tell a potential date you have an ostomy and they are horrified, think in the terms of, "Well, if he can't handle an ostomy, maybe he won't do well in a critical situation either or be a good provider, therefore, he isn't up to my standards." It may make your selection a bit easier and weed out the men from the mice. Then again, you'll probably have to deal with guys that just want to have a one night stand, whether you have an ostomy or not. It depends on what YOU want. You only live once though.
I hope this long post helped you in some way or form. You've taken the first step to dating again. Be brave. And remember, we're all here for you if you should need us.