There is no question from your description that your mother's behavior is completely inappropriate -- there is no "I think...".
This is not a "Prakash" issue, your mother has clearly inappropriate boundaries. There are many possible reasons for your mother's behavior, but Prakash is NOT the person to address the reasons with his mother. This is a terribly unfortunate situation in that as children (regardless of age), we commonly seek refuge in our mother's -- this is normal -- but these types of problems, usually leave us without that "safety net." And, to be certain, not by our choice. And this point must be made clear: "Parkash did not do anything wrong -- mother MADE the CHOICE to violate the boundaries." That is unfortunate.
Age is very important. Legally, there are certain remedies at various ages.
...when you were 17..., how old are you now? A rhetorical question that does not require an answer, and not that her behavior is appropriate at any age, at the risk of making an assumption, you sound to be a legal adult, in which case your ONLY REAL option seems clear, and not to put to fine a point on it: Get Out!
You need to extricate yourself from any further influence she is able to exert on YOUR life. As you stated, she has already interfered with "other women you were seeing" and "creating a rift" -- this is a classic abuse maneuver: Isolate the victim. And as your "world" has shrunk, she is now "become attractive" -- this too, is common among "prisoners."
This will be especially difficult for you Prakesh, and you'll likely need to seek help (Friends, government assistance, enlisting in the military may be an option, too). Based on your description, your mother is likely to guilt you into staying ("you'll never make it without me/us/your family", "but don't you love me", "Please, don't leave your mother"). The alternative is to subject yourself to continued abuse.
Also, you're Dad may not be aware of what is happening. However, abusers do not always act outside the purview of the family. There are many reasons for this as well, but these, too, are beyond Prakesh's control.
I hope I have been clear in that in no way is Prakesh at any fault in this situation, and IMHO your mother has sought to blur the boundaries, but because you are also indicating the acceptance of these "false" boundaries, I would very strongly recommend that you seek out a qualified therapist to help you focus on identifying and establishing boundaries, as well as establishing and maintaining healthy relationships.